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Q&A: Speed and speed limits

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 The requirement was loosened for rural interstates in 1987 and completely repealed in 1995.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, 35 states have speed limits of 70 mph or higher on some portion of their roadway systems.

• Table
• Map: maximum posted daytime speed limits on rural interstates

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

²In Kentucky, the speed limit may be increased to 70 mph on specific segments of highway upon the basis of an engineering and traffic investigation. On 07/10/07, highway officials increased the speed from 65 mph to 70 mph on Interstate 75 south of US 42, Interstate 71 west to the split to Louisville, and portions of Boone, Carroll, Gallatin, and Grant Counties.

³In sections of I-10 and I-20 in rural West Texas, the speed limit for passenger cars and light trucks is 80 mph. Speed limits may be established not to exceed 85 mph if the highway is designed to accommodate the higher speed and it has been determined by a traffic and safety engineering study to be reasonable and safe, effective September 1, 2011.

⁴Based on 2008 Utah House Bill 406, which became effective on May 5, 2008, portions of I-15 have a posted limit of 80 mph.

⁵In Virginia, the posted limit may be as high as 70 mph where indicated by lawfully placed signs, erected subsequent to a traffic engineering study, effective 07/01/10.