Speed limits in the United States

Speed limits in the United States are set by each state or territory. Speed limits in the United States vary according to the type of road and land use. These speed limits do not exceed eighty miles per hour. Increments of five miles per hour are used. Additionally, these limits sometimes differ according to the type of vehicle and the time of day. Occasionally there are also minimum speed limits.

Speed limits are set by the legislatures of states and territories, and sometimes by lesser authorities, either directly or by giving legal approval to government agencies.

For approximately thirteen years, no permanent posted speed limit in the United States exceeded 55 mph. Prior to that, speed limits were mostly the same as today, but more often lower or nonexistent in rural areas. The highest present posted speed limits are usually found in the inland West and the lowest limits are usually found in the Northeast and island territories, some limits fall outside these ranges. For example, some two-lane rural roads in Texas have 75 mph (120 km/h) speed limits, and there are two stretches of Interstate highway in West Texas with a daytime 80 mph (130 km/h) speed limit for passenger vehicles. In contrast, the highest speed limit on freeways in Hawaii is 60 mph (95 km/h).

speed limit of 55 mph

Charts

peed limits

This table contains the usual daytime speed limit, in miles per hour, on typical roads in each category. This is usually, but not always, the statutory speed limit.

Some states and territories have lower truck speed limits applicable to heavy trucks. If present, they are usually only on freeways or other high speed roadways.



*Freeway: Interstate highway or other state- or federally numbered road built to Interstate standards.
*Divided: State- or federally numbered road, generally 4 or more lanes, not built to Interstate standards, but with a median or other divider separating directions of travel.
*Undivided: State- or federally numbered road, generally 2 to 4 lanes, with no separator between directions of travel.
*County: County-owned roads that are generally not numbered by the state.
*Residential: Residential streets.

Examples of other speed-related laws

Minimum speed limits

In addition to the legally defined maximum speed, minimum speed limits may be applicable. Occasionally there are default minimum speed limits for certain types of roads, generally freeways. Posted minimum speed limit signs, however, are more prominent.

Comparable to the common basic speed rule, most jurisdictions also have laws prohibiting speeds so low they are dangerous or obstruct the normal flow of traffic.

Truck speed limits

Some jurisdictions set lower speed limits that are applicable only to large commercial vehicles like heavy trucks and buses. While they are called "truck speed limits", they generally do not apply to light trucks.

Theory

Because trucks are far heavier than other vehicles, they take longer to stop, are less adept at avoiding hazards, and have much greater crash energy. Therefore, it follows from basic physics that limiting truck speeds could reduce the severity and incidence of truck-related crashes.

However, the research record is mixed. A 1987 study finds that crash involvement significantly increases when trucks drive much slower than passenger vehicles, [http://www.fhwa.dot.gov/reports/tswstudy/Vol2-Chapter5.pdf, table V-4] suggesting that the difference in speed between passenger vehicles and slower trucks could cause crashes that otherwise may not happen. Furthermore, in a review of available research, the Transportation Research Board, part of the United States National Research Council, states " [no] conclusive evidence could be found to support or reject the use of differential speed limits for passenger cars and heavy trucks" (page 11) and "a strong case cannot be made on empirical grounds in support of or in opposition to differential speed limits" (page 109). [ [http://www.trb.org/news/blurb_detail.asp?id=2669 Managing Speed: Review of Current Practices for Setting and Enforcing Speed Limits ] ]

Two thirds (67%) of truck/passenger car crashes are the fault of the passenger vehicle. [ [http://www.fmcsa.dot.gov/documents/udarepo.pdf The Unsafe Driving Acts of Motorists in the Vicinity of Large Trucks ] ]

Night speed limits

While the basic speed rule, which requires drivers to drive a reasonable and proper speed at all times, is usually relied upon to regulate proper night speed reductions, numeric night speed limits generally may be established on roads where safety problems require a speed lower than what is self-selected by drivers. Exceptionally, Texas is the only state with default arbitrary nighttime speed limits.

Political considerations in the U.S.

Political and fiscal considerations affect speed enforcement.

Traffic violations have proved to be a great source of income for many jurisdictions. As a direct consequence, many state administrations have been reluctant to increase the speed limit on state roads. By keeping speed limits "unreasonably" low, the logical conclusion to this effort is that more motorists will appear to "speed". This gives law enforcement personnel the authority to issue traffic citations and thus improve the ticketing authorities's revenue. This policy has rarely been voiced or acknowledged. As a direct consequence of this, insurance companies have benefited as well. As motorists are charged with speeding violations their drivers licenses are assigned "violation points" (except for drivers licensed in South Dakota and other limited instances, where the law does not assign points for speeding violations). The more points accumulated (or demerited depending on the system) on a license the more risk an insurance company will associate with the driver. This has a direct consequence of increasing insurance premiums, resulting in greater revenue for the insurance company. Insurance companies rarely compete with each other as their premiums are determined by state guidelines. Thus, an authority that sets and enforces speed limits, such as a state government, regulates and taxes insurance companies, who also gain revenue from speeding enforcement. Furthermore, such an authority often requires "all" drivers to have policies with those same companies, solidifying the association between the state and auto insurers. If a driver cannot be covered under an insurance policy because of high risk the state will assume that high risk for a greater monetary amount; thus resulting in even more revenue generation for the state. [ [http://www.nationalreview.com/moore/moore062503.asp Stephen Moore on Speed Limits on National Review Online ] ] [ [http://research.stlouisfed.org/wp/more/2006-048/ St. Louis Fed: WP 2006-048C "Red Ink in the Rearview Mirror: Local Fiscal Conditions and the Issuance of Traffic Tickets" ] ]

Environmental speed limits

Reduced speed limits are sometimes proposed for air quality reasons in addition to other environmental concerns. Most notably, Texas has had specific environmental speed limits.

Metric speed limits

Though not common in the United States, a speed limit may be defined in kilometers per hour (km/h) as well as miles per hour (mph). The Federal Highway Administration's Manual on Uniform Traffic Control Devices, which provides guidelines for speed limit signage, states that "speed limits shown shall be in multiples of 10 km/h or 5 mph." [ [http://mutcd.fhwa.dot.gov/HTM/2003r1/part2/part2b1.htm FHWA - MUTCD - 2003 Edition Revision 1 Chapter 2B ] ] If a speed limit sign indicates km/h, the number is circumscribed and "km/h" is written below. Prior to 2003, metric speed limits were designated using the standard speed limit sign, usually with yellow supplemental "METRIC" and "km/h" plaques above it and below it, respectively. [ [http://lamar.colostate.edu/~hillger/laws/mutcd.html MUTCD and metric road signs in the US ] ] [ [http://www.alpsroads.net/roads/ny/i-87/n.html New York Roads - I-87 - Northway ] ]

Federal speed limit controls (55 mph)

National Maximum Speed Law (1974)

In response to the 1973 oil crisis, Congress enacted the National Maximum Speed Law that created the universal 55 mph speed limit.

The law was widely disregarded by motorists, even after the national maximum was increased to 65 mph in 1987 on certain roads. In 1995, the law was repealed, returning the choice of speed limit to each state.

2000s

Two prominent members of the United States Senate have speculated on reimposition of federal speed limit controls.

In 2006, Senator Hillary Clinton publicly supported reimposition of the 55 mph speed limit in a speech to the New York Press Club. [http://www.google.com/search?q=hillary+clinton+speed+limit]

On July 3, 2008, U.S. Senator John Warner, R-VA, wrote a letter to Energy Secretary Samuel Bodman asking to look into what speed limit would provide optimum gasoline efficiency given current technology. He said he wants to know if the administration might support efforts in Congress to require a lower speed limit. [ [http://www.cnn.com/2008/POLITICS/07/03/warner.speed.limit.ap/index.html National speed limit pushed as gas saver - CNN.com ] ]

Definition of speeding

For record keeping purposes, speeding is defined by the U.S. federal government as (1) exceeding speed limits or (2) driving too fast for conditions. [ [http://safety.fhwa.dot.gov/speed_manage/brochure.htm U.S. federal government brochure] ] Speeds in excess of speed limits account for most speed-related traffic citations; generally, "driving too fast for conditions" tickets are issued only after an incident where the ticket issuer found tangible evidence of unreasonable speed, such as a crash. A criticism of this definition of speeding is when speed limits are below the maximum safe speed, crashes that occur at speeds in excess of the limit can count as speed-related even when it is unclear whether the speed was unsafe.

Most speed-related crashes involve speed too fast for conditions. This includes conditions where speed under the effective limit may still be too fast, such as limited visibility or reduced road traction. [ [http://www.tfhrc.gov/safety/speed/speed.htm Synthesis of Safety Research Related to Speed, Publication No. FHWA-RD-98-154 ] ]

Variable speed limits offer some potential to reduce speed-related crashes. However, due to the high cost of implementation, they exist primarily on freeways. Furthermore, most speed-related crashes occur on local and collector roads. [http://safety.fhwa.dot.gov/speed_manage/docs/speeding_counts.pdf] Speed-related crashes can also occur at speeds below 30 miles per hour; for example, truck rollovers on exit ramps. [ [http://www.fmcsa.dot.gov/facts-research/research-technology/publications/vehicular-stability-systems.htm Vehicular Stability Systems (VSS) - Federal Motor Carrier Safety Administration ] ]

"Prima facie"

Most states have "absolute" speed limits, meaning that a speed in excess of the limit is illegal "per se". However, some states have "prima facie" speed limits. [http://www.mit.edu/~jfc/laws.html#types State Traffic and Speed Laws] This offers motorists a valid defense to a speeding charge if it can be proven that the speed was in fact reasonable and prudent.

A successful "prima facie" defense is rare. Not only does the burden of proof rest upon the accused, a successful defense may involve expert witnesses or other expenses well in excess of the cost of a ticket. Furthermore, because "prima facie" defenses must be presented in a court, such a defense is difficult for out of town motorists. Speed limits in Texas, Utah, and Rhode Island are "prima facie". Some other states have a hybrid system: speed limits may be "prima facie" up to a certain speed or only on certain roads.

Noteworthy jurisdictional distinctions

Alabama

In Alabama, trucks carrying hazardous materials are not to exceed 55 mph. [ [http://www.legislature.state.al.us/codeofalabama/1975%2009feb2004/32%2D5a%2D171.htm Section 32-5A-171 ] ]

Arizona

The default speed limit outside of “business or residential” districts in Arizona is 65 mph, within those districts the default speed limit is 25 mph. The school zone speed limit is 15 mph. Exceeding these limits only in the best of driving conditions is considered "prima facie" evidence of speeding. Altered speed limits, higher or lower, are not "prima facie". [Arizona Statutes Chapter 3 Article 6 28-701 [http://www.azleg.state.az.us/ArizonaRevisedStatutes.asp?Title=28|Arizona State Legislature] ]

The maximum posted speed limit on Interstate highways is 75 mph. This limit applies outside of urban areas, where 85 mph on any highway is considered “excessive”. Within urban areas 55 mph speed limit violations are given for “waste of a finite resource”, within a 10 mph threshhold. Within “business or residential” districts exceeding the speed limit by 20 mph is considered “excessive”. [Arizona Statutes Chapter 3 Article 6 28-701.02, 28-702.01, 28-702.04 [http://www.azleg.state.az.us/ArizonaRevisedStatutes.asp?Title=28|Arizona State Legislature] ]

Non-passenger vehicles in excess of thirteen tons, or “vehicles drawing a pole trailer” weighing more than 3 tons may not exceed 65 mph unless signs are posted that allow such a speed. Yet this does not differ from the default speed limit, and has the practical effect of requiring extra consideration for posting a standard speed limit sign in excess of 65 mph. [Arizona Statutes Chapter 3 Article 6 28-709 [http://www.azleg.state.az.us/ArizonaRevisedStatutes.asp?Title=28|Arizona State Legislature] ]

A non-numeric minimum speed limit is incorporated with the basic speed rule in Arizona, which also prohibits speeds that are less than “reasonable and prudent”. [Arizona Statutes Chapter 3 Article 6 28-701 [http://www.azleg.state.az.us/ArizonaRevisedStatutes.asp?Title=28|Arizona State Legislature] ]

California

California's "Basic Speed Law", [http://leginfo.ca.gov/cgi-bin/displaycode?section=veh&group=22001-23000&file=22348-22366 section 22350-22351] of the California Vehicle Code, defines the maximum speed at which a car may travel as a "reasonable and prudent" speed, given road conditions. The numerical limit set by Caltrans engineers for speed limit signs, generally found on all non-controlled-access routes, is considered a presumptive maximum "reasonable and prudent" speed.

Many speed limit signs are identified as "maximum speed", usually when the limit is 55 mph (90 km/h) or more. When the National Maximum Speed Law was enacted, California was forced to create a new legal signage category, "Maximum Speed", to indicate to drivers that the Basic Speed Law did not apply for speeds over the federally-mandated speed cap; rather, it would be a violation to exceed the fixed maximum speed indicated on the sign regardless of whether the driver's speed could be considered "reasonable and prudent".

A driver can receive a traffic citation for violating the Basic Speed Law even if their speed is below the posted "maximum speed limit" if road, weather or traffic conditions make that speed unsafe. However, because the Basic Speed Law establishes "prima facie" limits, not absolute ones, they can also defend against a citation for speeding "by competent evidence that the speed in excess of said limits did not constitute a violation of the basic speed law at the time, place and under the conditions then existing," per section 22351(b) of the California Vehicle Code. [http://www.dmv.ca.gov/pubs/vctop/d11/vc22351.htm Speed Law Violations California Vehicle Code, section 22351(b)] As Attorney David W. Brown says in his book Fight Your Ticket & Win in California, "a person traveling over the speed limit--but less than the usual 65 mph maximum speed (55 mph for two-lane undivided highways)--isn't necessarily violating the law" [cite book |title=Fight Your Ticket & Win in California |last=Brown |first=David W. |year=2005 |edition=11th edition |publisher=Nolo |location=Berkeley, CA |isbn=9781413306415 |chapter=Speed Violations and Radar |pages=4/2 |url=http://www.nolo.com/product.cfm/objectID/5049A39C-99F3-41FF-BA270821A98897B9/ ] and that "you can defend against a charge of violating the Basic Speed Law not only by showing you weren't exceeding the speed limit, but also by establishing that even if you were over the limit, your speed was nevertheless 'safe' under the circumstances." [cite book |title=Fight Your Ticket & Win in California |last=Brown |first=David W. |year=2005 |edition=11th edition |publisher=Nolo |location=Berkeley, CA |isbn=9781413306415 |chapter=Speed Violations and Radar |pages=4/10 |url=http://www.nolo.com/product.cfm/objectID/5049A39C-99F3-41FF-BA270821A98897B9/ ]

The speed limit on rural freeways, such as parts of I-5, I-8, I-10, I-15, I-40, U.S. 101 on the central coast, and SR 99 south of Madera and Fresno, have 70 mph (110 km/h) speed limits. Because I-80 passes exclusively through urban and mountainous areas, its highest speed limit is only 65 mph. In Los Angeles the maximum speed limit within the downtown area is 55 MPH. This includes the entire length of the Pasadena Freeway between [Pasadena, California|Pasadena and downtown Los Angeles; and portions of the Hollywood, Santa Ana, Santa Monica and Harbor Freeways. The default limit on 2-lane roads is 55 mph. However, Caltrans or a local agency can post a speed of up to 65 mph after an engineering study. [ [http://www.leginfo.ca.gov/cgi-bin/waisgate?WAISdocID=9352382531+0+0+0&WAISaction=retrieve WAIS Document Retrieval ] ]

All of these highways feature supplementary signage stating "AUTOS WITH TRAILERS/TRUCKS 55 MAXIMUM". Maximum truck/autos with trailers limit applies to trucks with 3 or more axles and all vehicles when towing. As of 2007, these signs are being replaced with signage stating "ALL VEHICLES WHILE TOWING 55 MAXIMUM".

In California, the Maximum Speed in school zones is 25 mph, but is in effect only if children are present within that school zone.

Connecticut

Limited-access divided highways have a minimum speed of 40 mph (65 km/h), [ [http://www.cga.ct.gov/2005/pub/Chap248.htm#Sec14-220.htm Connecticut General Statutes §14-220] ] but this is not always posted.

Delaware

In Delaware, only two roads have a 65 mph (105 km/h) speed limit: I-495 and Delaware Route 1. Interstate 95 is posted at 55 mph (90 km/h) and Interstate 295 is posted at 50 mph (80 km/h).

All rural two-lane state-owned roads have 50 mph (80 km/h) speed limits, while all urban speed limits, regardless of location, are held at 25 mph (40 km/h) for two-lane roads and up to 35 mph (55 km/h) for four-lane roads. Four lane highways such as US 13 and US 113 are normally posted at 55mph.

School zones have 20 mph (30 km/h).

Interstate 495, which forms a bypass around Wilmington, Delaware, features changeable speed limit signs for environmental purposes. These signs typically display a 65 mph speed limit, but this limit changes to 55 mph on days when air quality is a concern.

Florida

Florida raised its speed limit from the federally mandated 55 mph national limit (1974-1987) to 65 mph in 1987. In 1996, after the 1995 repeal of federal speed limit controls, Florida raised the speed limit to 70 mph on expressways, including rural Interstate highways, and limited access toll roads; 65 mph on rural 4-lane highways (including US and State highways); and 60 mph on rural 2-lane highways.

Florida typically does not post night speed limits, but there are a few exceptions. For the most part, these night time reduced speeds are located in wildlife preserves for such endangered species as the Florida panther and the key deer. Most of the Tamiami Trail through the Big Cypress National Preserve has a 45 mph night speed limit. [cite web|url=http://www.sherpaguides.com/florida/everglades/tamiami_trail_miami.html|title=Tamiami Trail—Miami to the Western Everglades|accessdate=2008-08-13] On some stretches of road where the speed limit is reduced at night, the daytime speed limit sign is not reflective so at night, only the night limit is visible.

County roads typically have 55 or 60 mph limits.

Florida's minimum speed limit on interstate highways is now 50 mph in most 70 mph zones, up from the previous 40 mph minimum. In 55 mph, and 65 mph urban interstate zones, the minimum remains 40 mph.Fact|date=November 2007

The State of Florida also does not impose a lower truck speed limit.

All interstate traffic is permitted to travel at the same speed.Fact|date=April 2008

School zones in Florida usually have 10 mph to 20 mph limits. Most have flashing yellow lights activated during the times they are in effect as well as accompanying signs which post the times these reduced speed limits are effective. All are strictly enforced and carry an increased penalty for violations.

Hawaii

Hawaii was the last state to raise its maximum speed limit after the National Maximum Speed Law was repealed in 1995. In 2002, after public outcry after a controversial experiment with speed enforcement using road safety cameras, the state Department of Transportation raised the speed limit to 60 mph on two stretches of road:
* Interstate H-1 between Kapolei and Waipahu, and
* Interstate H-3 between the Tetsuo Harano Tunnels and the junction with H-1. [ [http://starbulletin.com/2002/04/18/news/story5.html Honolulu Star-Bulletin Hawaii News ] ] All other freeways, including Interstate H-2, have a maximum speed limit of 55 mph, with the limit dropping to 50 mph in central Honolulu. Other highways generally have speed limits of 55 mph and in many cases much less. [ [http://www.hawaiihighways.com/FAQs-page2.htm#speed-limit Hawaii Highways - FAQs page 2 ] ]

Hawaii has a minimum speed posted along much of Interstate H-1 of only 10 mph below the speed limit. The minimum speed is usually 45 mph when the speed limit is 55, and 40 mph when the speed limit is 50.

Illinois

Interstate highways are usually posted with both minimum and maximum speed limits, except in some urban areas, particularly Chicago.

Indiana

In Indiana speed limits on Interstate highways are usually 70 mph (110 km/h) for cars and 65 mph (105 km/h) for trucks, except in urban areas, where it is generally 55 mph (90 km/h) in city centers and 65 mph (105 km/h) cars/60 mph (95 km/h) trucks in suburban areas. Prior to July 5, 2005, all Interstate highways were 65 mph and below.

Most non-Interstate highways are 55 mph, but some rural four-lane divided highways are set at 60 mph. These limits often decrease to 30-45 mph (50-70 km/h) approaching urban areas, and within cities a speed limit of 20–30 mph (30–50 km/h) is not uncommon, though larger arterial roads within cities may reach as high as 45 mph (70 km/h).

Iowa

Iowa's rural Interstate's speed limits are typically 70 mph (110 km/h), with no distinction made for trucks. Urban Interstate speed limits are usually set at 65 mph (105 km/h), with 55 mph speed limits set within cities, such as Interstate 235 in Des Moines. The Iowa DOT just recently increased the suburban speed limit on Interstate 235 to 60 mph, with 55 mph still posted for the downtown Des Moines area; 60 mph speed limits also exist on IA 58 and US 218 in Cedar Falls/Waterloo and on Interstate 380 outside of downtown Cedar Rapids.

Non-Interstate divided highways are signed at 65 mph with speeds dropping to 55 mph in urban areas. Two lane rural state and county highways have a 55 mph speed limit.

Rural Interstates have a minimum speed limit of 40 mph, and U.S. Highway 20 between Interstate 35 and Dubuque also has a 40 mph minimum speed, alongside a 65 mph maximum. Other four-lane divided rural highways are signed at 65 mph, with no minimum speed (with the purpose of allowing slow-moving farm vehicles to use the road as well).

Kentucky

In July 2007, Kentucky raised its rural freeway speed limits from 65 to 70 mph. [cite press release
title =Governor Fletcher Signs Speed Limit Bill | publisher =Commonwealth of Kentucky | date =2007-03-21 | url =http://governor.ky.gov/newsroom/pressreleases/20070321speed.htm | accessdate =2007-03-22
] Kentucky does still have limits of 55 in some urban areas (I-71/75 near Cincinnati, I-64 and Interstate 264 in Louisville) with one 50 MPH area approaching the Sherman Minton Bridge crossing the Ohio River into Indiana on I-64.

Louisiana

In August 2003, Governor Mike Foster announced speed and lane restrictions on trucks on the 18 mile (29 km) stretch of Interstate 10 known as the Atchafalaya Swamp Freeway. The restrictions lower the truck speed limit to 55 mph and restrict them to the right lane for the entire length of the elevated freeway. [ [http://www.dps.state.la.us/TIGER/lowerspdlimitsandlaneresttrucksI10.htm Lower Speed Limits and Lane Restrictions for Trucks on I-10 over Atchafalaya Basin ] ]

Michigan

Freeways in Michigan are usually posted with both minimum and maximum speeds. The minimum speed is usually 45 to 55 mph for all vehicles, despite a maximum speed limit of 60 mph for trucks — effectively permitting trucks only a 5 mph range of legal speeds.

Minnesota

A 70 mph speed limit is only allowed on Minnesota's rural freeways. A speed limit of 55 mph is typically used in urban areas where a higher speed limit might be used, but traffic congestion or other reasons require a lower speed limit. Examples include I-94, I-35W and I-35E in and around Minneapolis and Saint Paul. A speed limit of 60 mph is typically used in suburban areas such as I-494 and I-694 loops in the Twin cities metro area.

Non-Interstate divided highways (both freeways and rural expressways) such as sections of US-169 and US-212 have speed limits of 65 mph in rural areas and 55 or 60 mph in urban or suburban areas. Undivided sections have speed limits of 55 or 60 mph. Two lane county roads also have speed limits of 55 or 60 mph.

Mississippi

A speed limit of 70 mph is only allowed on Mississippi's rural freeways; only the Interstates (except I-110), U.S. Highway 78, Mississippi Highway 304, and a portion of U.S. Highway 82 have speed limits of 70 mph.

A speed limit of 60 is typically used in urban areas where a higher speed limit might be used, but traffic or geometric conditions constitute a lower speed limit. Examples include I-20 in Vicksburg, Jackson, and Meridian, I-55 in Jackson, I-59 in Laurel (the speed limit drops to 40 mph, due to a dangerous "S-curve") and Meridian, U.S. Highway 49 in Gulfport, U.S. Highway 61 at Tunica Resorts, US 78 in New Albany, and U.S. Highway 82 in Columbus.

House Bill 3, passed during the 2008 First Extraordinary Session of the state legislature, permits speed limits up to convert|80|mph|km/h|abbr=on to be posted on toll roads in the state; however, as of 2008, no such road has been constructed. [ [http://billstatus.ls.state.ms.us/documents/20081E/html/HB/0001-0099/HB0003SG.htm HB 3 (As Sent to Governor)] ]

Mississippi has a minimum speed of 30 mph on four-lane U.S. highways when no hazard exists. Strangely, there is no law for the minimum speed of the state's growing number of four-lane state highways. The minimum is 40 mph on Interstate highways and on four-lane U.S. designated highways which have a 70 mph speed limit, but this minimum shall be posted. [ [http://198.187.128.12/mississippi/lpext.dll?f=templates&fn=fs-main.htm&2.0 Mississippi Code §63-3-509] ] In 2004, Mississippi posted minimum speed limits (40 mph) on all rural Interstates, but this minimum speed limit was already state law before the widespread posting.

Missouri

Missouri recently began a two-year experiment with variable speed limits along Interstate 270 around St. Louis. Digital signs have been erected along the highway as well as additional signs alerting drivers about the use of variable speed limits. The limits will vary between 40 and 60 miles per hour, depending on traffic conditions, and could change by up to 5 mph every 5 minutes.Fact|date=October 2008

Interstate highways have minimum speed limits of 40 mph. [ [http://www.moga.mo.gov/statutes/C300-399/3040000011.HTM Missouri Revised Statutes §304-011] ]

Montana

Reasonable and prudent era

In the years before 1974's national 55 mph limit, and for three years after the 1995 repeal of the increased 65 mph limit, Montana had a non-numeric "reasonable and prudent" speed limit during the daytime on most rural roads. Montana Code Annotated (MCA) Section 61-8-303 said "A person . . . shall drive the vehicle . . . at a rate of speed no greater than is reasonable and proper under the conditions existing at the point of operation . . . so as not to unduly or unreasonably endanger the life, limb, property, or other rights of a person entitled to the use of the street or highway."

Montana law also specified a few numeric limits: a night speed limit, usually 55 or 65 mph (90–105 km/h), depending on road type; 25 mph (40 km/h) in urban districts and 35 mph (60 km/h) in construction zones.

The phrase "reasonable and prudent" is found in the language of most state speed laws. This allows prosecution under non-ideal conditions such as rain or snow when the speed limit would be imprudently fast.

No speed limit

On March 10, 1996, [ [http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=MT&vol=97&invol=486 FindLaw for Legal Professionals - Case Law, Federal and State Resources, Forms, and Code ] ] a Montana patrolman issued a speeding ticket to a driver traveling at 85 mph (140 km/h) on a stretch of State Highway 200. The 50 year-old driver was operating a 1996 Camaro with fewer than 10,000 miles (16,000 km) on the odometer. Although the officer gave no opinion as to what would have been a reasonable speed, the driver was convicted. The driver appealed to the Montana Supreme Court. The Court reversed the conviction in case No. 97-486 on December 23, 1998; it held that a law requiring drivers to drive at a non-numerical "reasonable and proper" speed "is so vague that it violates the Due Process Clause ... of the Montana Constitution".

Effective May 28, 1999, as a result of that decision, the Montana Legislature established a posted speed limit of 75 mph. [http://www.mdt.mt.gov/travinfo/speed_limit.shtml Official Montana Department of Transportation site]

75 mph speed limit

Despite this reversal, Montana's then Governor, Marc Racicot, did not convene an emergency session of the legislature. Montana technically had no speed limit whatsoever until June 1999, after the Montana legislature met in regular session and enacted a new law. The law's practical effect was to require numeric speed limits on all roads and disallow any speed limit higher than 75 mph (120 km/h).

Montana law still contains a section that says "a person shall operate a vehicle in a careful and prudent manner and at a reduced rate of speed no greater than is reasonable and prudent under the conditions existing at the point of operation, taking into account the amount and character of traffic, visibility, weather, and roadway conditions." However, this is a standard clause that appears in other state traffic codes and has the practical effect of requiring a speed lower than the speed limit where a lower speed is necessary to maintain a reasonable and prudent road manner.

Montana also has limited sections of night speed limits. [ [http://www.opi.state.mt.us/pdf/drivered/manual/ch4.pdf Section 4 Language of the road: signs, signals and pavement markings ] ]

New Hampshire

The highest speed limit in New Hampshire is 65 mph (105 km/h). It can be found on Interstate highways, the Everett Turnpike, and the New Hampshire Turnpike.

Provided that no hazard exists that requires lower speed, the speed of any vehicle not in excess of the limit is deemed to be "prima facie" lawful. The limit for "rural residential districts" and Class V highways outside the city or town compact is 35 mph. The limit for any "business or urban residence district" is 30 mph. School zones receive a 10 mph reduction in the limit 45 minutes before and after the beginning and end of a school day. The speed limit for a road work or construction area is 10 mph lower than the normal speed limit, but not more than 45 mph, when work is in progress. The speed limit for all other locations is 55 mph. The minimum limit that a speed can be set in a rural or urban district is 25 mph.

New Jersey

The common speed limit on a divided highway in New Jersey is 65 mph. Highways such as the New Jersey Turnpike (which uses variable electronic speed limit signs near Newark, New Jersey|Newark) south of Exit 12, the Atlantic City Expressway (north of the Garden State Parkway), the Garden State Parkway (north of Exit 163 in Paramus and south of the Sayreville toll barrier), New Jersey Route 55, I-80, I-287, and I-78 have 65 mph limits where speeding fines are doubled. Residential roads have 25 mph speed limits. Two-lane rural highways and two-lane county roads generally have 45 and 50 mph limits.

New Mexico

With the exception of wartime, New Mexico had no default numeric speed limit until the early 1950s. [history of speed limits, Ibiblio, 1998 [http://www.ibiblio.org/rdu/slaw1949.html] ] Prior to the national 55 mph limit in 1974, the speed limit on rural Interstates was 75 miles per hour during the day and 70 mph at night. Primary highways in open areas had daytime speed limits of 70 mph and nighttime ones of 60 mph. Secondary highways in open areas had daytime speed limits of 60 mph and nighttime ones of 50 mph. Before the end of federal speed controls, the maximum speed limit was 65 mph on Interstate routes and 55 mph elsewhere. In May of 1996 legislation enacted by Governor Gary E. Johnson raised the absolute speed limit in New Mexico to 75 mph.New Mexico Statutes Chapter 66 Article 7 Part 4 Statute 66-7-301 [http://www.conwaygreene.com/nmsu/lpext.dll?f=templates&fn=main-h.htm&2.0|New Mexico State Legislature] or [ [http://www.nmlaws.org/|nmlaws.org] ] Signs are posted on the vast majority of the mileage of Interstate routes to that effect.

New Mexico has six major freeway facilities which include three lengthy Interstate routes. Part of US-70 (as both a freeway and then a divided highway) between Las Cruces and Alamogordo is the only section of non-Interstate route to have the posted 75 mph limit. There is no statutory requirement for reduced speeds on urban freeways so that, for example at Santa Fe and Las Vegas the speed limit remains 75 mph on I-25. Nonetheless, there are posted 65 mph limits on freeways in more heavily urbanized areas such as Albuquerque and Las Cruces. Other reduced speed limits do exist, but the lowest posted speed limit under normal conditions on New Mexico's freeways is 55 mph.

Other state maintained roads have posted speed limits of up to 70 mph, although thirty mph to 65 mph is normal. Many rural two lane highways still have posted 55 mph limits for a variety of reasons.New Mexico Statutes Chapter 66 Article 7 Part 4 Statute 66-7-301, -303 [http://www.conwaygreene.com/nmsu/lpext.dll?f=templates&fn=main-h.htm&2.0|New Mexico State Legislature] or [ [http://www.nmlaws.org/|nmlaws.org] ]

A 65 mph left lane minimum speed limit is sometimes posted on 75 mph roads with steep grades, "slower traffic keep right" is also posted. On one-way roadways state law reserves the left and center lanes of two or more lanes for passing.New Mexico Statutes Chapter 66 Article 7 Part 4 Statute 66-7-305, -308, -311, -316, -317 [http://www.conwaygreene.com/nmsu/lpext.dll?f=templates&fn=main-h.htm&2.0|New Mexico State Legislature] or [ [http://www.nmlaws.org/|nmlaws.org] ] There are reduced advisory speed limits for some roads during poor weather. Speeding fines are doubled in construction zones and designated safety corridors, signs are often posted stating this. There are no longer night speed limits, nor are there any differential speed limits for heavy trucks.

There are two other statutory speed limits in New Mexico which are often altered, especially on urban arterials or even city or countywide:New Mexico Statutes Chapter 66 Article 7 Part 4 Statute 66-7-301, -303 [http://www.conwaygreene.com/nmsu/lpext.dll?f=templates&fn=main-h.htm&2.0|New Mexico State Legislature] or [ [http://www.nmlaws.org/|nmlaws.org] ] thirty miles per hour in a "business or residence district" and fifteen miles per hour near schools at certain times. For example, in Albuquerque the default speed limit is thirty miles per hour as per state law, but many streets have a different posted speed limit. Some school zones there have twenty mile per hour posted speed limits. The city of Santa Fe's default speed limit is twenty five miles per hour. [City of Santa Fe Code Chapter XXIV ExhibitA 12-6-1.2A [http://70.168.205.112/santafe_nm/lpext.dll?f=templates&fn=main-h.htm&2.0] ] Although there are no signs to make drivers aware of the altered limit, the limit is posted on most roads where it applies. The county of Los Alamos alters the urban default and absolute speed limits to twenty five miles per hour and 50 mph respectively, but posts signs at county lines.

New York

The highest speed limit in New York is 65 mph (105 km/h), which is found on most of the New York State Thruway and other rural Interstate highways. The "State Speed Limit" (a blanket or default speed limit for rural roads) is 55 mph (90 km/h), which is also the highest a non-expressway or parkway highway may have. Many 55 mph signs in New York thus read "State Speed Limit". The theme is followed, and many signs read "Area Speed Limit", "Town Speed Limit", "City Speed Limit" or "Village Speed Limit" with varying speeds shown below. In New York State, the default speed limit on any road not marked with a speed limit sign is 55 mph (unless local restrictions are stricter). [NYS DMV drivers Handbook] New York City and some other urbanized areas have a default speed limit of 30 mph (50 km/h) except where otherwise posted. The highest speed limit on expressways and parkways in New York City is 50 mph (80 km/h).

Governor George Pataki signed legislation in September 2003 that enables NYSDOT and NYSTA to raise speed limits to 65 mph on its roads that meet established design and safety standards. This legislation became active in March 2004, and has been used on over 100 miles worth of highway. An example of this is a 3-mile section of NY Route 7 (locally known as "Alternate Route 7") which connects Exit 7 of Interstate 87 (the Adirondack Northway) with Interstate 787, the main highway into the city of Albany. Prior to the new law, consent of the state legislature was necessary to enact a 65 mph speed limit, a process that could take months or years. In fact, New York was one of the last states in the United States to enable speed limits above 55 mph on any roads.

A minimum speed limit of 40 mph has been set on the entire length of Interstate 787 and the entire length of The Long Island Expressway. The New York State Thruway does not have a firm minimum speed, but there are signs advising drivers to use their flashers when traveling at speeds below 40 mph.

While New York does not have truck speed restrictions per se, the New England Thruway (Interstate 95) features "State Speed Limit 55" signs right next to "Truck Speed Limit 50" signs.

North Carolina

Along two lane rural primary and secondary roads outside municipal limits, the statutory speed limit is 55mph unless otherwise posted. Inside the municipal limits, the statutory speed limit is 35mph unless otherwise posted. The downtown statutory speed limit is 20mph unless otherwise posted. "Reduced Speed Ahead" signage is the norm whenever the speed limit drops at any level. Three to eight lane boulevards with or without center turn lanes, range from 35mph to 50mph within municipal limits statewide.

School zone speed limits are generally entail a 10 to 20 mph reduction below the original speed limit during open school hours of arrivals and departures. Such a speed limit would be posted when entering the school zone. Also, the default or modified speed limit is posted after leaving the school zone. A school zone speed limit cannot be less than 20mph.

Military bases are 50mph maximum. The exceptions are any numbered highways.Fact|date=October 2008

The state park speed limit is 25mph unless otherwise posted. These are not limited to places like Hanging Rock State Park and Mount Mitchell State Park.

The Blue Ridge Parkway is posted at 45mph however, there are occasional 35mph stretches. The National Park Service is responsible for highway maintenance and speed enforcement.

The county governments of North Carolina do not have any control over speed limits except municipalities. The exception of this rule are city-county governments like Charlotte.

60mph speed limits are growing in popularity into replacing 55mph boulevard and expressway segments throughout the state. The boulevard speed limit changes go against the NCDOT rationale behind signing 60mph speed limits along only freeway and expressway segments. As of June 1, 2008, some examples of the affected boulevards are US 17 north of Elizabeth City, US 74 east of Wadesboro and NC 11 in Pitt County. Some examples of the affected expressways are US 1 in northeastern Moore County, US 17 on bypass routes in Brunswick County, US 74 east of I-95, US 117 in Wayne County and US 220 in Rockingham County.

There is a default minimum speed limit on Interstate and primary highways only when signs are posted. The minimum is 40 mph if the maximum is 55 mph. The minimum is 45 mph if the maximum is at least 60 mph. These minimums do not apply to vehicles that are towing other vehicles. [ [http://www.ncleg.net/EnactedLegislation/Statutes/HTML/BySection/Chapter_20/GS_20-141.html North Carolina General Statutes §20-141(c)] ]

North Dakota

The highest speed limit found in North Dakota is 75 mph, which can be found on Interstates 29 and 94. Rural four-lane divided highways are 70 mph. Rural 2-Lane Federally numbered, and State Highways have 65 mph limits. Four-lane divided, Federally numbered, and State Highways that pass through cities have 25-65 mph limits. 65 mph speed limits on county roads can be found on portions in Ward County (CR 23) and Burleigh County (CR 10). Certain major county roads have 50-55 mph statutory limits for cars and 30-45 mph for trucks. A default 55 mph speed limit applies on other county roads. Speed limits on surface streets range from 30-40 mph. Residential streets are generally 15-25 mph. School zones are 15-25 mph.

Ohio

The maximum speed limit found on highways in Ohio is 65 miles per hour. Truck maximum speed applied to all vehicles with an empty vehicle weight greater than 8,000 pounds and all non-commercial buses.

The truck maximum speed is typically 55 miles per hour, 10 miles per hour lower than which is allowed for smaller vehicles. The only road in Ohio that allows trucks to exceed 55 mph is the Ohio Turnpike, which doesn't post a lower truck limit, allowing them to travel at 65 mph, in an effort to divert truck traffic off of the non-toll US-20 roadway.

Historically, Ohio had night speed limits of 50 miles per hour on Interstate highways. [http://www.odotonline.org/photoArchive/PhotoArchiveImages/Medium/50sign.jpg] Additionally, certain highways had speed limits as high as 75 miles per hour. [http://www.odotonline.org/photoArchive/PhotoArchiveImages/Medium/speedlimit%5B1%5D.jpg]

A minimum speed of 45 mph is posted on Interstate 70 in downtown Columbus, where the maximum limit is 55 mph. US-35 in Dayton has a minimum speed limit of 40 mph with a maximum of 55 mph.

Oklahoma

In Oklahoma, the maximum speed limit is 75 miles per hour on turnpikes and 70 mph on all other freeways. Most other rural highways have a 65 mph speed limit (although some rural divided highways have a 70 mph limit). Minimum speed limits that are 25 mph below the maximum speed limit are posted on more or less all Interstate highways . For example, on the turnpikes, which have a maximum speed limit of 75 mph, they are nearly always accompanied by a sign stating a minimum speed limit of 50 mph.

Oregon

Up until 2002, Oregon state law required that all speed limit signs remove the word "limit" from their display. The reasoning behind this is unknown but the practice has been known to produce some unusual number fonts. The spacing between and appearance of the numbers on the signs vary greatly depending on which jurisdiction made the sign. In 2002, the Oregon Department of Transportation permitted the inclusion of the word "limit" on speed signs and left it up to local government agencies to decide on whether "limit"-branded signs would be installed. Most have chosen not to change over with a few exceptions to the rule. Speed Limit 60 signs can be found on Interstate 5 through Salem and on Interstate 84 through east Portland. The City of Beaverton has been the most liberal in retrofitting the standard-form Speed Limit sign, presumably because the "SPEED" signs do not use a standard number font and are likely more expensive to make. Whenever a "Speed" sign is damaged or vandalized in Beaverton city limits, a "Speed Limit" sign takes its place.

Throughout the late 1990s the Oregon state legislature passed multiple bills that would have raised the speed limit to 75 miles per hour on rural Interstate highways and up to 70 mph on certain rural two lane highways in the eastern portions of the state. Each year Governor John Kitzhaber vetoed the bill. In 2003, the Oregon state legislature passed a bill that would have raised the maximum permissible speed limit on Interstate highways to 70 mph for cars with a 5 mph differential for trucks, up from the previous 65 mph limit for cars with a 10 mph differential, this bill was signed into law by then newly elected Governor Ted Kulongoski. In 2004 the Oregon Department of Transportation decided to not implement the increase out of concerns that it would not be safe to have trucks traveling at 65 mph. Prior to the National Maximum Speed Law, the speed limit on Oregon interstates could be as high as 75 mph. Oregon remains the only state west of the Mississippi River to have a maximum state speed limit that is under 70 mph.

In 2004, a law was passed revising Oregon's school speed limit laws. In school zones, on roads with speed limits of 30 mph or below, drivers were required to slow to 20 mph 24 hours a day, 365 days a year, regardless of whether or not children were present. This replaced most 'when children are present' placards. If the speed limit was 35 mph or higher, the school zone limit would be imposed either by flashing yellow lights or a placard denoting times and days of the week when the limit was in effect. The at-all-times rule was highly unpopular with motorists and was widely ignored. In fact, it is likely that this law has led to a reduced acceptance of school speed limits, regardless of how and when they are in effectFact|date=April 2008. In 2006, the law was revised again, taking away the 'at all times' requirement and replacing it with a time-of-day system (usually school days, 7 a.m. to 5 p.m.). School crossings with flashing yellow lights remain.

Pennsylvania

In 1940, when the Pennsylvania Turnpike was opened between Irwin and Carlisle, the entire 110 mile limited-access toll road did not have a speed limit, similar to that of the German Autobahns. In 1941, a speed limit of 70 mph (110 km/h) was established, only to be reduced to 35 mph (55 km/h) during the war years (1942–45). After WWII, the limit was raised to 70 mph on the four-lane sections, with the two-lane tunnels having 50 mph (80 km/h) for cars and 40 mph (65 km/h) for trucks. Prior to the 1974 federal speed limit law, all Interstates and the Turnpike had a 65 mph (105 km/h) speed limit on rural stretches and 60 mph (100 km/h) speed limit in urban areas.

In 1995, the state raised the speed limit on rural stretches of Interstate highways and the Pennsylvania Turnpike system to 65 mph (105 km/h), with urban area having a 55 mph (90 km/h) limit. In 1997, PennDOT raised the speed limit to some rural non-Interstate highway bypasses to 65 mph (105 km/h). In 2005, with the change in the designation of "urban zones" in the state, the entire lengths of both the Pennsylvania Turnpike's east-west mainline and Northeast Extension were given 65 mph (105 km/h) limits, except at the tunnels and through the very winding 5.5 mile (9 km) eastern approach to the Allegheny Mountain Tunnel.

On non-freeway roads, speed limits are generally held at 65 mph (105 km/h) for rural four-lane roads, 55 mph (90 km/h) for rural two-lane roads, 45 mph (70 km/h) for urban four lane and state-owned two lane roads, 35 mph (55 km/h) for major roads in residential areas, 25 mph (40 km/h) for most municipal residential streets, including main north–south and east–west roads in county seats, and 15-20 mph (25 km/h) for school zones during school arrival and departure times only. It is also only in effect on days that particular school is in session. Many schools have signs that blink when the school speed limit is in effect. The speed is determined by the school's proximity to the road. There is no reduced school speed on divided highways, even if the school sits right beside the highway.

The Pennsylvania Turnpike has a minimum speed limit of 15 mph below the speed limit. Therefore, the minimum speed is 50 mph when the speed limit is 65 mph, and 40 mph when the speed limit is 55 mph. The Pennsylvania Turnpike Commission also states that vehicles that cannot maintain this speed on a level road may not use the turnpike. This minimum speed is not generally posted. Motorists are required to use flashers when traveling below 50 MPH on Pennsylvania freeways with a 65 MPH speed limit and below 40 MPH for highways with a 55 MPH limit.

Puerto Rico

The US territory of Puerto Rico regulates and posts speed limits in miles per hour, although highway signage for distances are in kilometers. Tolled "Autopistas" can have speed limits up to 65 mph, while other expressways have speed limits up to 60 mph. The maximum statutory speed limit for any expressway may in theory be 65 mph. The rural default speed limit is 45 mph but may be increased to 55 mph. In residential areas, only multilane roads have limits up to 35 mph, other roads are restricted to a maximum speed of 25 mph. Only rural school zones have the higher 25 mph limit. Speed limits for "heavy motor vehicles", such as school buses, are always 10 mph lower than that allowed for lighter vehicles, except in urban school zones where the limit is 15 mph. Vehicles carrying hazardous materials are limited to 30 mph in rural areas and 15 mph in urban ones. [§ 5122. Maximum lawful speed limits and penalties., Subchapter IV, Chapter 27, Title 9 of the Laws of Puerto Rico [http://michie.lexisnexis.com/puertorico/lpext.dll?f=templates&fn=main-h.htm&cp=prcode] ]

outh Dakota

Shortly after the December 1995 repeal of the 65/55 mph National Maximum Speed Law, South Dakota raised its general rural speed limits to 75 mph on freeways and 65 mph on other roads. Almost a decade after posting the 75 mph limit, average speeds on South Dakotan rural freeways remain at or below the speed limit. [http://www.sddot.com/pe/data/Docs/SPEED2006.pdf] South Dakota also has the distinction of being the only state that does not assign points to one's driving record for speeding convictions.

Texas

Texas is the only state that does not prescribe a speed limit for each road type. Any rural road—two lane, four lane, freeway, or otherwise—that is numbered by the state or federal government (United States Numbered Highways and Interstate highways) has a 70 mph (110 km/h) statutory limit. The law generally allows changing the 70 mph limit only if a study recommends a different limit. [http://tlo2.tlc.state.tx.us/statutes/docs/TN/content/htm/tn.007.00.000545.00.htm#545.353.00 TRANSPORTATION CODE CHAPTER 545. OPERATION AND MOVEMENT OF VEHICLES] ] Unlike other Texas county roads, which have 60 mph maximum speed limits, Harris County's toll road authority may post up to 70 mph limits on its tollway system. [Texas Statutes, Transportation Code, [http://tlo2.tlc.state.tx.us/statutes/docs/TN/content/htm/tn.007.00.000545.00.htm#545.355.00 § 545.355. AUTHORITY OF COUNTY COMMISSIONERS COURT TO ALTER SPEED LIMITS] , paragraph (e)] ]

I-10 within the El Paso city limits has a minimum speed limit of 45 mph.

Night speed limits in Texas

Texas statutorily prescribes a 65 mph (105 km/h) night speed limit on all roads. In practice, roads with a daytime limit below 65 mph retain that lower limit at night. While the Texas Transportation Commission has the power to raise the night speed limit to 70 mph, it has never done so. Virtually all 70 mph or higher speed limit signs have an accompanying 65 mph night speed limit sign. Two exceptions:
#a 55 mph night speed limit for trucks on farm to market roads, complementing the statutory 60 mph truck day limit on these roads. (This is a holdover from Texas's truck speed limits.)
#a 55 mph night speed limit on county roads (except for Harris County Toll Road Authority-owned toll freeways).

Environmental speed limits in Texas

Texas is the first state to lower speed limits for air quality reasons. In roughly a 50 mile (80 km) radius of the HoustonGalveston and DallasFt. Worth regions, the Texas Commission on Environmental Quality convinced [cite web|url=http://www.dot.state.tx.us/tdotnews/trnscrpt/2000/0500trns.htm|title=Texas Transportation Commission meeting minutes|date=2000-05-25|accessdate=2007-07-24|work=Texas Department of Transportation Search for words "environmental speed limits", and refer to the paragraphs containing the first instance of the word and subsequent paragraphs.] the Texas Department of Transportation to reduce the speed limit on all roads with 70 mph (110 km/h) or 65 mph (105 km/h) speed limits by 5 mph. [http://www.tnrcc.state.tx.us/oprd/sips/speedlimit.html] This was instituted as part of a plan to reduce smog-forming emissions in areas out of compliance with the federal Clean Air Act. [ [http://www.tceq.state.tx.us/implementation/air/sip/speedlimit.html Vehicular Speed-Limit Reduction - Texas Commission on Environmental Quality - www.tceq.state.tx.us ] ]

Initial studies found that lower speed limits could bring the areas roughly 1.5% closer to compliance. [ [http://people.smu.edu/acambre/esl-nctcog.htm Effectiveness of ESLs ] ] However, follow up studies found that the actual reduction is far less:
#The emissions modeling software initially used, MOBILE 5a, overestimated the emissions contribution of speed limit reductions. Rerunning the models with the next generation software, MOBILE 6, produced dramatically lower emissions reductions.
#Speed checks in the Dallas area performed 1 year after implementation of speed limit reductions show that actual speed reductions are only about 1.6 mph, a fraction of the anticipated 10% (5.5 mph) speed reduction.With both of these facts combined, it is possible that the speed limit reductions only provide a thousandth of the total emissions reductions necessary for Clean Air Act compliance. [ [http://people.smu.edu/acambre/eslEPA102402.htm Letter to EPA about Environmental Speed Limits ] ]

In mid-2002, all speed limits in the Houston–Galveston area were capped at 55 mph (90 km/h). [http://www.tnrcc.state.tx.us/oprd/sips/dec2000hga.html] Facing immense opposition, [http://www.ghasp.org/publications/55chronicle.html] [ [http://www.heartland.org/Article.cfm?artId=1097 Scientist testifies against 55 mph speed limit - by Environment & Climate News staff - The Heartland Institute ] ] poor compliance, [ [http://tti.tamu.edu/cts/cts/organization/policy_initiatives_analysis/projects/pid_houston.stm TTI: Groups: : ] ] and the finding that lowered speed limits produced only a fraction of the originally estimated emissions reductions, [ [http://yosemite1.epa.gov/r6/press.nsf/0/b7d1c1828ed43ff586256c67005d51c4?OpenDocument EPA Region 6 News Release: Speed Limits in Houston/Galveston Area May Be Increased 11/04/2002 ] ] the TCEQ relented and reverted to the 5 mph reduction scheme. [http://www.tnrcc.state.tx.us/oprd/sips/dec2002hga.html]

In 2003, the Texas Legislature prospectively banned environmental speed limits effective September 1, 2003. The wording of the bill allows environmental speed limits already in place to remain indefinitely; no new miles of roadway may be subjected to environmental speed limits, however. [ [http://www.dfwinfo.com/trans/env_speed_limits/ North Central Texas Council of Governments - NCTCOG.org ] ]

This law has allowed interesting inconsistencies. Generally, all primary arterial roads within the inner loops of Texas cities have speed limits of 60 mph (95 km/h) or lower, so they were not subjected to environmental speed limits. Arterial roads between the inner loop and the outer loop generally have 65 mph (105 km/h) limits, and arterial roads outside the outer loop generally have 70 mph (110 km/h) limits.Fact|date=February 2008 (Note that this is only the typical pattern and is not prescribed by law.) In at least one case—TX 121 between I-35W and I-820 in Ft. Worth—the speed limit rises from 60 mph to 65 mph as one crosses IH-820 approaching downtown,Fact|date=February 2008 contravening the standard.

Truck speed limits in Texas

mail.

Whenever the speed limit on a road was above this threshold, separate truck speed limit signs were posted. These signs disappeared when all speed limits were capped at 55 mph (90 km/h) in 1974, but reappeared with the introduction of 65 mph (105 km/h) limits in 1987. Effective September 1, 1999, Texas repealed truck speed limits on all roads except farm to market and ranch to market roads. [http://www.landlinemag.com/Archives/1999/august99/legislative_news.html]

Even after Texas repealed the truck speed limit, the Harris County Toll Road Authority erroneously retained the separate truck speed limits on its tolled freeways. The separate truck speed limits were removed with the 2002 adoption of the 55 mph environmental speed limit. The signs did not reappear when a 65 mph limit was imposed, but the truck speed limit sign posts are still standing as of August 2008.

2001 and 2003 statutes allowing 75 and 80 mph speed limits in certain areas of west and south Texas only apply to passenger vehicles. Truck speed limits remain 70 mph, so separate truck speed limit signs are slowly reappearing on these roads.

Due to the enormous unpopularity of a 55 mph speed limit cap that was imposed on the greater Houston area in 2002, the Texas Commission on Environmental Quality examined alternatives. Analysis suggested that the vast majority of emissions reductions from a 55 mph limit was from reduced heavy truck emissions. A proposed alternative was to restore passenger vehicle limits but retain a 55 mph truck speed limit. Concerns about safety problems and enforceability of such a large differential (up to 15 mph on many roads) scuttled that proposal, and a compromise plan, described above, was enacted that retained uniform, but still reduced, speed limits.

75 mph and 80 mph limits

Texas statutorily allows the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with average populations of fewer than 15 people per square mile. The same statute also allows 80 mph (130 km/h) speed limits on I-10 and I-20 in certain counties named in the statute, all of which happen to be rural, in west Texas, and have a low population density. Daytime truck limits are capped at 70 mph, and nighttime speed limits remain 65 mph for all vehicles. (Nothing prohibits nighttime speed limits from being raised to 70 mph, but the Department has not elected to do so.)

In 2001, the Texas Legislature allowed the Texas Department of Transportation to post 75 mph (120 km/h) speed limits in counties with fewer than 10 people per square mile. [http://www.capitol.state.tx.us/cgi-bin/tlo/textframe.cmd?LEG=77&SESS=R&CHAMBER=H&BILLTYPE=B&BILLSUFFIX=00299&VERSION=5&TYPE=B] This has the practical effect of only allowing 75 mph speed limits in the most sparsely populated counties, all of which are generally well west of a line stretching from San Antonio to Odessa. In 2005, the Texas Legislature revised this law, allowing 80 mph (130 km/h) limits on I-10 and I-20 in certain rural counties in west Texas. This bill also revised the eligibility for 75 mph speed limits: now eligible counties can have up to 15 persons per square mile. This did not substantially increase the miles of roadway eligible for higher limits, however. [http://www.texhwyman.com/h_imgs/txpopdens.jpg]

On May 25, 2006, the Texas Transportation Commission has approved 80 mph speed limits, [ [http://www.txdot.gov/oda/newsrel/026%2D2006.htm TxDOT Odessa District News Release ] ] and signs are posted.

In a widely printed Associated Press story about the 80 mph speed limit, [ [http://www.foxnews.com/story/0,2933,197072,00.html FOXNews.com - Texas Raises Rural Speed Limits to 80 MPH - Local News | News Articles | National News | US News ] ] Texas is incorrectly reported as having legalized 75 mph limits in 1999. In fact, the bill that would have done this, HB 3328 [http://www.capitol.state.tx.us/cgi-bin/db2www/tlo/billhist/billhist.d2w/report?LEG=76&SESS=R&CHAMBER=H&BILLTYPE=B&BILLSUFFIX=03328] by Pete Gallego, died in conference committee just before the Texas Legislature's session ended. This bill would have, in effect, set 75 mph as the statutory speed limit on any rural road numbered by the state or federal government, and it would have enacted—not simply allowed—an 80 mph speed limit on I-10 and I-20 in any county with fewer than 25,000 residents.

While Texas's 80 mph limit is higher than any limit authorized by another state, it is equivalent to the 130 km/h recommended speed on the Autobahn and the actual 130 km/h rural expressway speed limit in thirteen other European countries. [http://en.wikipedia.org/wiki/Speed_limit#Table]

Because Texas law allows 75 mph speed limits on any road numbered by the state or federal government, it is the only state with 75 mph limits on two-lane roads. Several west Texas two-lane roads carry 75 mph limits, including portions of US 90 [.http://www.houstonfreeways.com/modern/2005-01_road_trip_us90.aspx] No other state has a limit higher than 70 mph on any two-lane road.

85 mph limits

The legislation creating the Trans-Texas Corridor allows speed limits of up to 85 mph (140 km/h) [ [http://tlo2.tlc.state.tx.us/statutes/docs/TN/content/htm/tn.007.00.000545.00.htm#545.3531.00 TRANSPORTATION CODE CHAPTER 545. OPERATION AND MOVEMENT OF VEHICLES ] ] on roads built under the program. However, no such roads have been built as of January 2008. The language of the statute does not prohibit the Texas Transportation Commission from raising the truck speed limit or the night speed limit on these roads.

United States Virgin Islands

For "motorcars, pick-up trucks, or motorcycles", the fastest speed limit in this territory is 55 mph and is found on one road, the divided Melvin E. Evans Highway on the island of St. Croix. Outside of towns, these vehicles are limited to 35 mph unless posted lower, except on the above mentioned divided highway and parts of Centerline Road, which is limited to 40 mph. Within towns, these vehicles are limited to twenty miles per hour. [Section 494.speed limits, Chapter 43, Part II, Title 20 of the Virgin Islands Code [http://michie.lexisnexis.com/virginislands/lpext.dll?f=templates&fn=main-h.htm&cp=] ]

"Motor trucks and busses" are limited to 40 mph on St. Croix's main divided highway, 30 mph on other highways outside of towns, and ten miles per hour within towns. [Section 494.speed limits, Chapter 43, Part II, Title 20 of the Virgin Islands Code [http://michie.lexisnexis.com/virginislands/lpext.dll?f=templates&fn=main-h.htm&cp=] ]

Utah

In Utah, there is a minimum speed limit of 45 mph on Interstate highways, when conditions permit.

Virginia

Virginia has three relevant provisions on speed limits. First, in urban areas where the speed limit is set on freeways to 55 mph, where there are High Occupancy Vehicle lanes, drivers in those lanes will be permitted to drive at 65 mph. The Code of Virginia deems driving more than 19 miles over the speed limit to be reckless driving, as is driving 80 or more miles per hour on any road. [ § 46.2-862 of the Code of Virginia is available at http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+46.2-862] The Chesapeake Bay Bridge-Tunnel has a minimum speed limit of 40 mph.

References

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