Speed Limit Laws
In 1974, Nixon and his administration imposed a maximum speed limit of 55 mph. The District of Columbia is the only place where the 55 mph limit is still used, mainly because it is the home of the federal legislature and a major urban center.
The 55 mph limit was imposed to reduce fuel usage, which at the time had many issues, especially due to the Cold War. In 1988, the administration approved raising the NMSL to 65 mph due to the stability of fuel prices. This was short-lived, as, in 1995, Congress finally decided to allow states to create their own guidance and enforcement regarding their speed limit, as they would know the best way to proceed in that landscape.
Most states make distinctions between speed limits in different areas. Rural freeways usually have the highest maximum speed within a state. Many states have a lower maximum for freeways that run through urban areas. Residential areas generally have the lowest maximum speed limit within a given state.
Speed Limits on Rural Freeways
Thirteen states have a speed limit of 75 mph, and another twenty-four have rural freeway limits of 70 mph.
The lowest maximum speed limit is in Hawaii, where drivers can only reach 60 mph on rural freeways. Ten additional states limit speeds to 65 mph.
Speed Limits on Urban Freeways
Most states have a lower maximum speed when driving on urban freeways because of increased traffic. New Mexico, North Dakota, South Dakota, Mississippi, Tennessee, Kentucky, Michigan, Delaware, and Maryland all have the same maximum speed for freeways, regardless of their location.
The highest maximum speed for urban freeways is 75 mph. This is valid in Texas, New Mexico, North Dakota, and South Dakota. Five more states (Utah, Kentucky, Michigan, Mississippi, and Tennessee) have a maximum speed limit of 70 mph. Most states have a 60-65 mph speed limit on urban freeways.
Again, Hawaii has the lowest maximum speed limit at 50 mph. The District of Columbia and ten states in the mid-Atlantic and New England have speed limits of 55 mph.
Speed Limits in Residential Zones
Because of the number of homes and people, residential zones usually have their own speed limits. These are generally lower than other speed limits within the state to increase safety for residents.
Texas, New Mexico, North Dakota, and West Virginia have residential speed limits of 55 mph. The lowest maximum speed limit in a residential zone is 25 mph, enforced in fifteen states and the District of Columbia.
Regional Speed Limit Trends
Looking at this data, some general trends become clear. States with lower populations generally have higher maximum speed limits. Additionally, most states with high-speed limits are located in the south and southwest of the country.
Most northeastern states have very similar speed limit laws. Their speed limits are generally some of the lowest in the country. This probably results from the poor weather conditions like snow and ice that make driving less safe in this area of the country.