Study Links Higher U.S. Speed Limits to Fatalities

April 05, 2019 at 10:39 AM

Nearly 37,000 people have died in the U.S. over the last 25 years due to increased speed limits, according to the Insurance Institute for Highway Safety.

The authors say every 5 mph increase in speed limits raises fatalities 8% on highways/freeways and 3% on other roads. From 1993 to 2017, the total deaths attributed to higher speeds on highways was more than 13,600 and some 23,100 on other roads, IIHS says.

The study estimates that 5% (1,900) of the more than 37,100 traffic-related fatalities in 2017 could have prevented if speed limits hadn't risen since 1993. At that time, no state had a maximum speed limit greater than 65 mph.

The calculations were based on annual traffic fatalities per mile traveled for each state, speed limits and other variables. The latter includes such things as seatbelt usage rates, the number of young drivers (ages 16-24) and changes in unemployment.

The U.S. had a nationwide 55 mph speed limit from 1974—implemented in response to the 1973 oil crisis—to 1987, when some state limits were raised to 65 mph. Congress repealed national speed laws in 1995, allowing states to set their own limits.

Today, 41 states have maximum limits of 70 mph or higher. Six states have 80 mph limits, and drivers in Texas can legally drive 85 mph on some roads.

IIHS notes that its research tracks with other studies over the years that have linked higher speed limits to increased fatalities. The group also points out that motorists typically travel slightly faster than posted speeds, regardless of the legal limit.

In addition to “reasonable” limits, IIHS advocates for high-visibility enforcement and traffic engineering improvements to help reduce accidents. The group is hosting a forum with the Governors Highway Safety Assn. later this month in Charlottesville, Va., to discuss various issues and initiatives.