USA Speed Limits by State

Why do the maximum speed limits in the USA vary by state?

Speed limits in the USA are set by the state rather than at national level and are posted in miles per hour (mph) and generally use increments of 5mph. Some states have reduced speed limits for trucks and when driving at night. The general rule of thumb is that states with vast open freeways will tend to have higher speed limits, whereas smaller states with higher populations and busier freeways are likely to have the slower maximum speed limits.

Washington D.C unsurprisingly has the lowest speed limit in the USA at just 55mph, although technically it doesn’t have any rural freeways, so its fastest roads are urban freeways. Texas has the highest speed limit in the USA at a brisk 85mph. Taking all states into account, the average maximum speed limit in the USA by state is 69.8mph, whilst the median speed limit is 70mph.

Are there Minimum Speed Limits in the USA

Some states impose a minimum speed limit of 40mph, typically on freeways (motorways) to ensure that traffic using them keeps to a safe speed and flow of traffic.

Are there Speed Limits at Night in the USA

Some states impose reduced speed limits when driving at night. Where these are applied, any speed limit sign will state the general speed limit for the road (white sign / black text) with the night time speed limit immediately below with a black sign with white text. Whilst rare, you’re likely to see night time speed limits in the following locations;
 

• Arizona – where no street lights present
• Florida – named ‘Panther Zones’ or Panther X-ing’
• Colorado – Highway 13 drops from 65mph by day to 55mph at night
• Washington – Highway 20 drops to 45mph at night due to high number of deer on the road at night

Rural Freeway Speed Limits by State

*Speed limit in Utah increased to 75-80mph on interstate highways where clearly signed, otherwise remain at 65.

History of speed limits in the US

The first speed limit was officially set in Connecticut in 1901 where motor vehicles were limited to 12 mph in towns and cities and 15 mph on country roads. There are stories of speed limits being set as early as 1652 however pertaining to non-motorized vehicles, where the colony of New Amsterdam (now New York) passed a law restricting wagons, carts and sleighs (horse drawn) may not be rode or driven at a gallop (or faster). Penalties started at 2 Flemish pounds (equivalent of $150 in today’s money).

Q: How fast is a gallop?
A: An average horse will gallop at 25 to 30 mph (40-48 kph)
 

US National 55 mph Speed Limit - National Maximum Speed Law (NMSL)

As traffic laws and regulations were introduced across the USA (New YorK City introduced the first official traffic code in 1901), speed limits varied from state to state, however in 1974, President Nixon introduced a national limit of 55 mph. Driven by rising fuel prices and a poor economy, its aim was to reduce fuel usage and lower the cost motoring. As fuel price concerns subsided and car safety improved, the NMSL was amended to allow speeds of up to 65 mph on certain rural roads in 1987 and 1988.

In 1995 US Congress handed the control of speed limits back to individual states, allowing elected state representatives to determine speed limits and enforcement.
 

What is the Fastest Speed Limit in the US?

Texas as the fastest speed limit in the US at 85 mph. The Texas State Highway 130 (SH 130), often referred to as Pickle Parkway. The 41 mile (66km) section from SH 45 and I-10 has the fastest designated speed limit in the US at 85 mph, meaning the journey would take just under 29 minutes to complete at the maximum speed limit (28:56).
 

Does the US have kph (km/h) speed limit signs?

Metric speed limits were abolished in the USA in 2009 following amendments to the Federal Highway Administration's Manual on Uniform Traffic Control Devices (MUTCD). The 2003 version permitted speed limits to be applied in multiples of 10 kph or 5 mph. Where speed limits were signed in kilometres per hour (kph), the value was circumscribed and km/h was denoted below the speed limit. Speed limits were not signed in metric (km/h) from as early as 1995 when federal funds were no longer available for metric speed limit signs. Metric speed limit signs in the USA are rare and gradually being phased out to avoid confusion.
 

US Speed Limit Signs