Speed limits in the United states - wikipedia Speed limits in the United states See also : Speed limits in the United States ( rail ), Speed limits in the United States by jurisdiction, and Road signs in the United States Main articles : Speed limit and Speed limits by country Speed limits in the United States are set by each state or territory. Highway speed limits can range from an urban low of 35 mph ( 56 km / h ) to a rural high of 85 mph ( 137 km / h ). Speed limits are typically posted in increments of five miles per hour ( 8 km / h ). Some states have lower limits for trucks and at night, and occasionally there are minimum speed limits. Most speed limits are set by state or local statute, although each state allows various subdivisions ( counties and municipalities ) to set a different, generally lower, limit. The highest speed limits are generally 70 mph ( 113 km / h ) on the West Coast and the inland eastern states, 75 -- 80 mph ( 121 -- 129 km / h ) in inland western states, along with Arkansas and Louisiana, and 65 -- 75 mph ( 105 -- 121 km / h ) on the Eastern Seaboard. Alaska, Connecticut, Delaware, Massachusetts, New Jersey, New York, Puerto Rico, Rhode Island, and Vermont have a maximum limit of 65 mph ( 105 km / h ), and Hawaii has a maximum limit of 60 mph ( 97 km / h ). Washington, D.C. and the U.S. Virgin Islands have a maximum speed limit of 55 mph ( 89 km / h ), and Guam and the Samoa have speed limits of 45 mph ( 72 km / h ). Unusual for any state east of the Mississippi River, much of I - 95 in Maine north of Bangor allows up to 75 mph ( 121 km / h ), as well as up to 600 miles of freeways in Michigan. Portions of the Idaho, Montana, Nevada, South Dakota, Texas, Utah, and Wyoming road networks have 80 mph ( 129 km / h ) posted limits. The highest posted speed limit in the entire country can be found on the Texas State Highway 130, and it is 85 mph ( 137 km / h ). For 13 years ( January 1974 -- April 1987 ), federal law withheld Federal highway trust funds to states that had speed limits above 55 mph ( 89 km / h ). From April 1987 through December 8, 1995, an amended federal law disincentivized speed limits above 65 mph ( 105 km / h ). A standard sign indicating a speed limit of 80 miles per hour ( mph ), a night - time speed limit of 65 mph, and a truck speed limit of 55 mph A speed limit sign entering a school zone, along with a warning light above Variety used in Oregon, omitting the word LIMIT. The typeface of the numerals varies significantly due to its non-standard design. See Oregon speed limits. Contents 1 Overview 1.1 Speed limits 1.2 Examples of related laws 2 History 2.1 Federal speed controls 3 Minimum speed limits 4 Truck speed limits 4.1 Theory 5 Night speed limits 6 Political considerations 6.1 Financial concerns 6.2 Environmental concerns 6.3 Metric speed limits 6.4 Definition of speeding 6.4. 1 Prima facie 7 See also 8 References 8.1 Law Review Overview Speed limits This table contains the most usual posted daytime speed limits, in miles per hour, on typical roads in each category. The values shown are not necessarily the fastest or slowest. They usually indicate, but not always, statutory speed limits. 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. Washington allows for speeds up to 75 miles per hour ( 121 km / h ), but the highest posted signs are 70 miles per hour ( 110 km / h ). Mississippi allows speeds up to 80 mph ( 130 km / h ) on toll roads, but no such roads exist. Oklahoma removed the maximum speed of 75 from its laws, though no road been posted higher than 75. Legend : Freeway : Interstate Highway or other state or U.S. Route built to Interstate standards. Divided rural : State or U.S. route, generally with four or more lanes, not built to Interstate standards, but with a median or other divider separating directions of travel. Undivided rural : County, State, or U.S. route, generally with two to four lanes, with no separator between directions of travel. Residential Street / residential : Residential streets, business districts, or School zones. 5 miles per hour ( 8.0 km / h ) 10 miles per hour ( 16 km / h ) 15 miles per hour ( 24 km / h ) 20 miles per hour ( 32 km / h ) 25 miles per hour ( 40 km / h ) 30 miles per hour ( 48 km / h ) 35 miles per hour ( 56 km / h ). 40 miles per hour ( 64 km / h ) 45 miles per hour ( 72 km / h ) 50 miles per hour ( 80 km / h ) 55 miles per hour ( 89 km / h ) 60 miles per hour ( 97 km / h ) 65 miles per hour ( 105 km / h ) 70 miles per hour ( 110 km / h ) 75 miles per hour ( 121 km / h ) 80 miles per hour ( 130 km / h ) 85 miles per hour ( 137 km / h ) Further information : Speed limits in the United States by jurisdiction State or territory Freeway ( rural ) Freeway ( trucks ) Freeway ( urban ) Divided ( rural ) Undivided ( rural ) Residential Alabama 70 mph ( 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 mph ( 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Alaska 65 mph ( 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 45 -- 65 mph ( 72 -- 105 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) American Samoa -- -- 45 mph ( 72 km / h ) 25 -- 45 mph ( 40 -- 72 km / h ) 20 mph ( 32 km / h ) Arizona 65 -- 75 mph ( 105 -- 121 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 45 -- 65 mph ( 72 -- 105 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Arkansas 70 -- 75 mph ( 113 -- 121 km / h ) 70 mph ( 110 km / h ) 60 -- 65 mph ( 97 -- 105 km / h ) 65 mph ( 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 30 mph ( 48 km / h ) California 65 -- 70 mph ( 105 -- 113 km / h ) 55 mph ( 89 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 65 mph ( 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 25 -- 30 mph ( 40 -- 48 km / h ) Colorado 65 -- 75 mph ( 105 -- 121 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Connecticut 65 mph ( 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 55 mph ( 89 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 20 -- 40 mph ( 32 -- 64 km / h ) Delaware 65 mph ( 105 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 45 -- 60 mph ( 72 -- 97 km / h ) 35 -- 50 mph ( 56 -- 80 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) District of Columbia -- 55 mph ( 89 km / h ) -- -- 25 mph ( 40 km / h ) Florida 70 mph ( 113 km / h ) 45 -- 70 mph ( 72 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 60 mph ( 89 -- 97 km / h ) 20 -- 50 mph ( 32 -- 80 km / h ) Georgia 70 mph ( 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 25 -- 45 mph ( 40 -- 72 km / h ) Guam -- -- 45 mph ( 72 km / h ) 35 -- 45 mph ( 56 -- 72 km / h ) 35 mph ( 56 km / h ) Hawaii 55 -- 60 mph ( 89 -- 97 km / h ) 35 -- 50 mph ( 56 -- 80 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 45 -- 60 mph ( 72 -- 97 km / h ) 25 mph ( 40 km / h ) Idaho 70 -- 80 mph ( 110 -- 130 km / h ) 70 mph ( 113 km / h ) 60 -- 65 mph ( 97 -- 105 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 25 -- 30 mph ( 40 -- 48 km / h ) Illinois 70 mph ( 113 km / h ) 45 -- 70 mph ( 72 -- 113 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) Indiana 70 mph ( 113 km / h ) 65 mph ( 105 km / h ) 50 -- 70 mph ( 80 -- 113 km / h ) 55 -- 60 mph ( 89 -- 97 km / h ) 50 -- 55 mph ( 80 -- 89 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) Iowa 70 mph ( 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 mph ( 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 25 mph ( 40 km / h ) Kansas 75 mph ( 121 km / h ) 60 -- 75 mph ( 97 -- 121 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) Kentucky 70 mph ( 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 25 -- 45 mph ( 40 -- 72 km / h ) Louisiana 70 -- 75 mph ( 113 -- 121 km / h ) 50 -- 70 mph ( 80 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 20 -- 45 mph ( 32 -- 72 km / h ) Maine 70 -- 75 mph ( 113 -- 121 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 25 mph ( 40 km / h ) Maryland 65 -- 70 mph ( 105 -- 113 km / h ) 40 -- 65 mph ( 64 -- 105 km / h ) 55 mph ( 89 km / h ) 50 -- 55 mph ( 80 -- 89 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Massachusetts 65 mph ( 105 km / h ) 45 -- 65 mph ( 72 -- 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) Michigan 70 -- 75 mph ( 113 -- 121 km / h ) 65 mph ( 105 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 25 mph ( 40 km / h ) Minnesota 65 -- 70 mph ( 105 -- 113 km / h ) 45 -- 60 mph ( 72 -- 97 km / h ) 60 -- 65 mph ( 97 -- 105 km / h ) 55 -- 60 mph ( 89 -- 97 km / h ) 30 mph ( 48 km / h ) Mississippi 70 mph ( 113 km / h ) 60 mph ( 97 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 25 mph ( 40 km / h ) Missouri 70 mph ( 113 km / h ) 45 -- 70 mph ( 72 -- 113 km / h ) 60 -- 70 mph ( 97 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 25 -- 40 mph ( 40 -- 64 km / h ) Montana 75 -- 80 mph ( 121 -- 129 km / h ) 65 mph ( 105 km / h ) 65 mph ( 105 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Nebraska 75 mph ( 121 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 mph ( 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 25 mph ( 40 km / h ) Nevada 70 -- 80 mph ( 113 -- 129 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 -- 75 mph ( 105 -- 121 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) New Hampshire 65 -- 70 mph ( 105 -- 113 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 55 mph ( 89 km / h ) 35 -- 55 mph ( 56 -- 89 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) New Jersey 65 mph ( 105 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 55 mph ( 89 km / h ) 30 -- 55 mph ( 48 -- 89 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) New Mexico 75 mph ( 121 km / h ) 55 -- 75 mph ( 89 -- 121 km / h ) 55 -- 75 mph ( 89 -- 121 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 55 mph ( 32 -- 89 km / h ) New York 65 mph ( 105 km / h ) 35 -- 55 mph ( 56 -- 89 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 35 -- 55 mph ( 56 -- 89 km / h ) 20 -- 45 mph ( 32 -- 72 km / h ) North Carolina 65 -- 70 mph ( 105 -- 113 km / h ) 50 -- 60 mph ( 80 -- 97 km / h ) 55 -- 60 mph ( 89 -- 97 km / h ) 55 mph ( 89 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) North Dakota 75 mph ( 121 km / h ) 55 -- 75 mph ( 89 -- 121 km / h ) 70 mph ( 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Northern Mariana Islands -- 45 mph ( 72 km / h ) Ohio 70 mph ( 113 km / h ) 50 -- 70 mph ( 80 -- 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 45 -- 70 mph ( 72 -- 113 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Oklahoma 70 mph ( 113 km / h ) ( 75 mph ( 121 km / h ) turnpikes ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 25 mph ( 40 km / h ) Oregon 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 50 -- 60 mph ( 80 -- 97 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Pennsylvania 65 -- 70 mph ( 105 -- 113 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 55 mph ( 89 km / h ) 40 -- 55 mph ( 64 -- 89 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Puerto Rico 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) - - 35 -- 55 mph ( 56 -- 89 km / h ) 35 mph ( 56 km / h ) Rhode Island 65 mph ( 105 km / h ) 50 -- 55 mph ( 80 -- 89 km / h ) 55 mph ( 89 km / h ) 50 mph ( 80 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) South Carolina 70 mph ( 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 45 -- 55 mph ( 72 -- 89 km / h ) 20 -- 30 mph ( 32 -- 48 km / h ) South Dakota 75 -- 80 mph ( 121 -- 129 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 45 mph ( 32 -- 72 km / h ) Tennessee 70 mph ( 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 35 -- 55 mph ( 56 -- 89 km / h ) 30 mph ( 48 km / h ) Texas 75 -- 85 mph ( 121 -- 137 km / h ) 55 -- 75 mph ( 89 -- 121 km / h ) 75 mph ( 121 km / h ) 55 -- 75 mph ( 89 -- 121 km / h ) 25 -- 30 mph ( 40 -- 48 km / h ) U.S. Virgin Islands -- -- 55 mph ( 89 km / h ) 25 -- 45 mph ( 40 -- 72 km / h ) 20 -- 25 mph ( 32 -- 40 km / h ) Utah 75 -- 80 mph ( 121 -- 129 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Vermont 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 55 mph ( 89 km / h ) 50 -- 55 mph ( 80 -- 89 km / h ) Virginia 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 55 -- 60 mph ( 89 -- 97 km / h ) 55 mph ( 89 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Washington 70 -- 75 mph ( 113 -- 121 km / h ) 60 mph ( 97 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 65 -- 70 mph ( 105 -- 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 20 -- 50 mph ( 32 -- 80 km / h ) West Virginia 70 mph ( 113 km / h ) 55 -- 65 mph ( 89 -- 105 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 20 -- 55 mph ( 32 -- 89 km / h ) Wisconsin 70 mph ( 113 km / h ) 50 -- 65 mph ( 80 -- 105 km / h ) 65 mph ( 105 km / h ) 55 mph ( 89 km / h ) 20 -- 35 mph ( 32 -- 56 km / h ) Wyoming 75 -- 80 mph ( 121 -- 129 km / h ) 65 mph ( 105 km / h ) 70 mph ( 113 km / h ) 55 -- 70 mph ( 89 -- 113 km / h ) 30 mph ( 48 km / h ) legend : Freeway : Interstate Highway or other state - or federally numbered road built to Interstate standards. Divided : State - or federally numbered road, generally with four or more lanes, not built to Interstate standards, but with a median or other divider separating directions of travel. Undivided rural : County, State, or U.S. route, generally with two to four lanes, with no separator between directions of travel. Residential Street / residential : Residential streets, business districts, or School zones. 5 miles per hour ( 8 km / h ) 10 miles per hour ( 16 km / h ) 15 miles per hour ( 24 km / h ) 20 miles per hour ( 32 km / h ) 25 miles per hour ( 40 km / h ) 30 miles per hour ( 48 km / h ) 35 miles per hour ( 56 km / h ) 40 miles per hour ( 64 km / h ) 45 miles per hour ( 72 km / h ) 50 miles per hour ( 80 km / h ) 55 miles per hour ( 89 km / h ) 60 miles per hour ( 97 km / h ) 65 miles per hour ( 105 km / h ) 70 miles per hour ( 113 km / h ) 75 miles per hour ( 121 km / h ) 80 miles per hour ( 129 km / h ) 85 miles per hour ( 137 km / h ) Examples of related Laws State Typical fine Recklessness threshold or enhanced penalty Absolute / prima facie Ticket dismissal options Point system Arizona Over 35 mph ( 56 km / h ) in a school zone, over 20 mph ( 32 km / h ) above the posted speed limit, or over 85 mph ( 137 km / h ) regardless of the posted speed limit. Prima facie ( Absolute above 85 mph ( 137 km / h ) ) Defensive driving school ( requires court approval for criminal speeding tickets ). Point system leading to fines, potential license suspension, increased insurance rates, and potential jail time ( if criminal ). North Carolina $10 -- $50 plus court costs. Speeding fines in work zones and school zones are $250 plus court costs. Over 15 mph ( 24 km / h ) over limit at a travelled speed of greater than 55 mph ( 89 km / h ) or over 80 mph ( 130 km / h ) Absolute Prayer for judgment continued ( PJC ) available depending on the court and subject to their discretion, but not available for charges of exceeding a speed limit by more than 25 mph ( 40 km / h ). Point system may lead to license suspension. Exceeding the speed limit by more than 15 mph ( 24 km / h ) with a speed of greater than 55 mph ( 89 km / h ) or travelling faster than 80 mph ( 130 km / h ) results in a minimum 30 - day license suspension. Pennsylvania $35 plus court and other costs. All fines doubled in active work zones. Over 30 mph ( 48 km / h ) over limit Absolute None Point system leads to mandatory driver education and possible license suspension. Texas $1 -- $20 plus court fees. Doubled in active school zones when children are present or construction zones when workers are present. Various additional `` fees '' assessed by the state essentially increase the fine by around $100 on all tickets. None Prima facie Defensive driving ( once per year ) or deferred disposition ( restrictions vary, but generally at least 4 per year ), but only valid if : Texas resident, Speed under 25 mph ( 40 km / h ) above limit and under 95 mph ( 153 km / h ), and Not in construction zone where workers are present or active school zone. Not a Commercial Driver License ( CDL ) holder. Point system is annual surcharge only. No provision for license suspension if surcharges are paid. Rhode Island Prima facie One dismissal every 3 years for speed 14 mph ( 23 km / h ) or less over limit. Virginia Up to $250 School zone : up to $250 additional Work zone : up to $500 $200 civil penalty in certain towns 20 mph ( 32 km / h ) over limit or over 80 mph ( 130 km / h ). Absolute Point system leading to fines, suspension, and mandatory driver education. History One of the first speed limits in what would become the United States ( at the time, still a British colony ) was set in Boston in 1701 by the board of selectmen ( similar to a city council ) : Ordered, That no person whatsoever Shall at any time hereafter ride or drive a gallop or other extream pace within any of the Streets, lanes, or alleys in this Town on penalty of forfeiting three Shillings for every such offence, and it may be lawfull for any of the Inhabitants of this Town to make Stop of such horse or Rider untill the name of the offender be known in order to prosecution Federal speed controls In 1973, Congress enacted a national speed limit of 55 mph ( 89 km / h ). Some states, such as Washington, enacted lower speed limits. For more details on this topic, see National Maximum Speed Law. In response to the 1973 oil crisis, Congress enacted the National Maximum Speed Law that created the universal 55 miles per hour ( 89 km / h ) speed limit. Whether this reduced gasoline consumption is debated and the impact on safety is unclear ; studies and opinions of safety advocates are mixed. The law was widely disregarded by motorists, even after the national maximum was increased to 65 miles per hour ( 105 km / h ) on certain roads in 1987 and 1988. In 1995, the law was repealed, returning the choice of speed limit to each state. Upon that repeal, there was effectively no speed limit on Montana 's interstates for daytime driving ( the nighttime limit was set at 65 mph ) from 1995 to 1999, when the state Supreme Court threw out the law as `` unconstitutionally vague. '' The state legislature enacted a 75 mph daytime limit in May of 1999. As of May 15, 2017, 41 states have maximum speed limits of 70 mph or higher. 18 of those states have 75 mph speed limits or higher, while 7 states of that same portion have 80 mph speed limits. 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. Comparable to the common basic speed rule, most jurisdictions also have laws prohibiting speeds so low they are dangerous or impede the normal and reasonable 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 The research record is mixed. A 1987 study finds that crash involvement significantly increases when trucks drive much slower than passenger vehicles, 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 can not be made on empirical grounds in support of or in opposition to differential speed limits '' ( page 109 ). One study has claimed that two thirds ( 67 % ) of truck / passenger car crashes are the fault of the passenger vehicle. Night speed limits This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. ( November 2014 ) Night speed limit in the Key Deer habitat on the Florida Keys. Note the nonreflective backing of the day speed limit number. At night, only the number on the lower sign is visible in the headlights. The basic speed rule requires drivers adjust speeds to the conditions. This is usually relied upon to regulate proper night speed reductions, if required. Numeric night speed limits, which generally begin 30 minutes after sunset and end 30 minutes before sunrise, are occasionally used where, in theory, safety problems require a speed lower than what is self - selected by drivers. Examples include : Some streets in Tucson, Arizona without street lights. Some Florida roads near Southwest Florida International Airport near Cape Coral / Fort Myers. ( Most of these roads are labeled as `` Panther Zones '' or `` Panther X-ing '' areas. ) Daniels Parkway Ext., a four - lane divided highway near SW Florida International Airport with a 50 mph ( 80 km / h ) daytime limit, and a night speed limit of 45 miles per hour ( 72 km / h ) is considered by many to be a speed trap. This road joins neighboring SR 82, a two - lane road with a 60 mph ( 97 km / h ) speed limit. Colorado Highway 13, with a 65 mph ( 105 km / h ) day / 55 mph ( 89 km / h ) night speed limit beginning 7.1 miles north of I - 70 from north of Rifle to Colorado Highway 64 south of Meeker. Rural Colorado Highway 13 is 55 miles per hour ( 89 km / h ) at night north of Meeker all the way to the Wyoming state line. Highway 20 in Washington state between Twisp and Pateros has a 45mph speed limit due to high amounts of deer ( and other wildlife ) activity. Deer carcasses can be seen along the road all throughout summer Some states create arbitrary night speed limits applicable to entire classes of roads. Until September 2011, Texas had a statutory 65 mph ( 105 km / h ) night speed limit for all roads with a higher limit. Montana has a statutory 65 mph ( 105 km / h ) night speed limit on all federal, state, and secondary roads except for Interstates. Political considerations Financial concerns Traffic violations can be a lucrative income source for jurisdictions and insurance companies. For example : Westlake, TX took in $42,000 per citizen over nine years for its speed traps. Insurance companies may receive several billions of dollars annually in traffic ticket surcharges. A study by the Federal Reserve of St. Louis found that traffic ticket writing increases when government revenue decreases. 2008 debates over traffic enforcement in Dallas County, TX involved concerns of lost profits if ticketwriting decreased. In Massachusetts, half of the ticket money goes to the police department that writes the speeding ticket, the other half goes to fund the court that convicts the speeder or collects the fine from them. 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 can not 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. When a speed limit is used to generate revenue but has no safety justification, it is called a speed trap. The town of New Rome, Ohio was such a speed trap, where speeding tickets raised up to $400,000 per year to fund the police department of a 12 - acre village with 60 residents. Environmental concerns Reduced speed limits are sometimes enacted for air quality reasons. The most prominent example includes Texas ' environmental speed limits. Metric speed limits The values of metric speed limits in the US are to be circumscribed in accordance with the MUTCD. 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. '' 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. In 1995, the National Highway System Designation Act prohibited use of federal funds to finance new metric signage. Definition of speeding Either of the following qualifies a crash as speed - related in accordance with U.S. government rules : Exceeding speed limits. Driving too fast for conditions. 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 the `` exceeding speed limits '' definition of speeding is twofold : When speed limits are arbitrary, such as when set through political rather than empirical processes, the speed limit 's relationship to the maximum safe speed is weakened or intentionally eliminated. Therefore, a crash can be counted as speed - related even if it occurs at a safe speed, simply because the speed was in excess of a politically determined limit. The effective limit may still be too fast for certain conditions, such as limited visibility or reduced road traction or even low - speed truck rollovers on exit ramps. 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, which generally have far lower speed limits and prevailing speeds than freeways. 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. This allows motorists to defend against a speeding charge if it can be proven that the speed was in fact reasonable and prudent. 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. For example, speed limits in California up to 55 mph, or 65 mph on highways, are prima facie, and those at or above those speeds are absolute. A successful prima facie defense is rare. Not only does the burden of proof rest upon the accused, a successful defense may involve expenses well in excess of the cost of a ticket, such as an expert witness. Furthermore, because prima facie defenses must be presented in a court, such a defense is difficult for out - of - town motorists. See also Driver License Compact Non-Resident Violator Compact Solomon curve Traffic violations reciprocity Transportation safety in the United States References Jump up ^ `` Nixon Approves Limit of 55 MPH ''. The New York Times. January 3, 1974. pp. 1, 24. Retrieved July 22, 2008. ( subscription required ) ^ Jump up to : Blair, William G. ( 4 April 1987 ). `` 65 - m.p.h. Signs Sprout Out West, but New York Region Holds Off ''. The New York Times. Retrieved 21 August 2016. Jump up ^ `` H.R. 2 -- 100th Congress ( 1987 -- 1988 ) : Surface Transportation and Uniform Relocation Assistance Act of 1987 ''. Congress.gov. Library of Congress. 2 April 1987. Retrieved 21 August 2016. Jump up ^ `` Alabama Law Enforcement Agency ''. Dps.alabama.gov. Retrieved 2017 - 07 - 07. Jump up ^ `` Alabama Law Enforcement Agency ''. Dps.alabama.gov. Retrieved 2017 - 07 - 07. Jump up ^ American Samoa Code Section 22.0323 ( 1 ), and Frommer 's ( 2 ) Jump up ^ Arizona Statutes Chapter 3 Article 6 State Legislature Jump up ^ `` California Highways with 70 MPH Speed Limits ''. ca.gov. Retrieved 11 July 2016. Jump up ^ `` Subchapter VIII. Speed Restrictions. ''. Delaware State Legislature. May 19, 2008. Jump up ^ `` Speed limit to jump on Del. 1 near Dover Air Force Base ''. Retrieved 5 July 2017. Jump up ^ District of Columbia Municipal Regulations Title 18 -- Vehicle and Traffic ( March 1997 ), chapter 22 `` Moving Violations '' ( 3 ) ( 4 ) Jump up ^ `` Florida Department of Transportation ''. state.fl.us. Retrieved 11 July 2016. Jump up ^ `` HB 674 -- Maximus Speed Limots ; vehicles having greater than 6 wheels. ''. Georgia House of Representatives. May 21, 2008. 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Speed Limits in the United States Road Limits ( by jurisdiction ) Rail Limits National Mandates World War II ( 1942 -- 1945 ) National Maximum Speed Law ( 1974 -- 1995 ) Speed limits in North America Sovereign states Antigua and Barbuda Bahamas Barbados Belize Canada Costa Rica Cuba Dominica Dominican Republic El Salvador Grenada Guatemala Haiti Honduras Jamaica Mexico Nicaragua Panama Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines Trinidad and Tobago United States Dependencies and other territories Anguilla Aruba Bermuda Bonaire British Virgin Islands Cayman Islands Curaçao Greenland Guadeloupe Martinique Montserrat Puerto Rico Saint Barthélemy Saint Martin Saint Pierre and Miquelon Saba Sint Eustatius Sint Maarten Turks and Caicos Islands United States Virgin Islands Retrieved from `` https://en.wikipedia.org/w/index.php?title=Speed_limits_in_the_United_States&oldid=801092164 '' Categories : Road transportation in the United States Speed limits by country United States transportation law Hidden categories : Pages containing links to subscription - only content Webarchive template wayback links All articles with unsourced statements Articles with unsourced statements from July 2015 Articles needing additional references from November 2014 All articles needing additional references Articles with unsourced statements from July 2016 Articles with unsourced statements from May 2014 Talk Contents About Wikipedia Français Nederlands Română Edit links This page was last edited on 17 September 2017, at 16 : 30. 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Question: what's the highest speed limit in the usa
Answer: 85 mph (137 km/h)