In the United States, speed limits are set by each state or territory, and states have also allowed counties and municipalities to enact typically lower limits. Highway speed limits can range from an urban low of 25 mph (40 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), and some states have lower limits for trucks, some also have night and/or minimum speed limits. 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, Louisiana, Maine, and Michigan; and 65–70 mph (105–113 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) .
It is important to note that the National Maximum Speed Limit (NMSL) was a provision of the federal government of the United States 1974 Emergency Highway Energy Conservation Act that effectively prohibited speed limits higher than 55 miles per hour (89 km/h) . However, Congress repealed the NMSL in 1995, fully returning speed limit-setting authority to the individual states.
