Speed limits in the United States by jurisdiction

Speed limits in the United States vary depending on jurisdiction, with 75 to 80 mph (120 to 130 km/h) common in the Western United States and 65 to 70 mph (100 to 110 km/h) common in the Eastern United States. States may also set special speed limits for trucks and night travel along with minimum speed limits. The highest speed limit in the country is 85 mph (140 km/h), which is posted on a single stretch of tollway in rural Texas.

In Alabama, it is illegal to drive at a speed that is not "reasonable and prudent" for the current conditions and hazards. Drivers must also not drive so slow that they impede the flow of traffic. If the speed limit is not otherwise posted, it is:

Trucks carrying hazardous materials are not to exceed 55 miles per hour (89 km/h).

In Alaska, several roads carry a 65-mile-per-hour (105 km/h) speed limit: a majority of the Parks Highway between Fairbanks and Willow (excepting slower zones through Nenana, Denali Park, Cantwell, and Healy), most of the Richardson Highway between Valdez and North Pole, a 35-mile (56 km) stretch of the Glenn Highway between Wasilla and Anchorage, the Seward Highway freeway in Anchorage between 36th Avenue and Rabbit Creek Road, and other non-freeway parts of the Seward Highway farther south. The Minnesota Drive Expressway features a 60-mile-per-hour (97 km/h) speed limit. Engineering studies are needed to define which road segments to post a speed limit higher than 55 miles per hour (89 km/h).

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