March 2015

The following table lists the speed limits for various types of roads in the 50 states and the District of Columbia. If a state has different speed limits for commercial trucks, they are listed separately.

In many states, the maximum speed limit that state or local authorities can establish depends on whether the road is a rural or urban interstate, a noninterstate limited-access highway, or another type of road. Limited-access highways are multiple-lane roads with restricted access via exit and entrance ramps, rather than intersections. The limited-access highways that make up the national interstate highway system are divided into urban and rural sections, based on population density figures from the U.S. Census Bureau. The designations may be adjusted by state and local governments to reflect planning and other issues.

Speed limits have traditionally been the responsibility of the states. In the mid-1970s, however, Congress established a national maximum speed limit by withholding highway funds from states that maintained speed limits greater than 55 mph. The requirement was loosened for rural interstates in 1987 and completely repealed in 1995. As of today, 38 states have speed limits of 70 mph or higher on some portion of their roadway systems.

Maximum limit may apply only to specified segments of interstate.

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1In Hawaii, the maximum speed limit is established by county ordinance or by the director of transportation.

2In Idaho, the speed limit may be increased to 80 mph on specific segments of highway on the basis of an engineering and traffic investigation.

3The Illinois law allows Cook, DuPage, Kane, Lake, Madison, McHenry, St. Clair and Will Counties to opt-out by adopting an ordinance that sets a lower maximum speed limit, empowering counties to make adjustments based on their own local needs. These counties have a maximum large truck speed limit of 60 mph outside of urban districts and 55 mph inside urban districts.

4In Kentucky, the speed limit may be increased to 70 mph on specific segments of highway on the basis of an engineering and traffic investigation.

52013 New Hampshire House Bill 146 raised the speed limit from 65 to 70 mph on the portion of I-93 from mile marker 45 to the Vermont border.

6Sections of I-10 and I-20 in West Texas and sections of Highway 45 in Travis County have a speed limit for passenger cars and light trucks of 80 mph. Speed limits of up to 85 mph may be established if the highway is originally constructed and designed to accommodate the higher speed and it has been determined by an engineering study to be reasonable and safe. State Highway 130 (portions toll) has a posted limit of 85 mph, effective Oct. 2012.

7In Utah, the speed limit may be increased beyond 75 mph on any freeway or limited access highway on the basis of an engineering and traffic investigation, effective May 12, 2014. The highest posted limit in Utah is currently 80mph.

8In Wyoming, the speed limit may be increased to 80 mph on specific segments of highway on the basis of an engineering and traffic investigation.