Higher Speed Limits Don't Cause More Deaths, Study Finds

A new study of changing speed limits in the United States finds no evidence that higher limits fuel more deaths.

Political scientist Robert Yowell of the Stephen F. Austin State University in Texas examined shifts in speed limit laws over the past few decades.

Highway speed limits were initially throttled in the 1970s in response to the gas shortage. In the 1980s the focus shifted to public safety. Yet in 1995, Congress returned all speed limit authority back to the states, and many states raised their top highway speeds.

While limits ranged from 75 mph to 55 and back again, no significant increase in fatalities per mile driven are evident.

In fact, from 1968 to 1991, the fatality rate per 100 million miles declined by 63.2 percent.

Yowell attributes the decrease to safer cars, increased use of seat belts, an increase in the minimum legal drinking age, and better road maintenance.

"Automobile safety features and enforcement emerge as important factors in increasing highway safety," Yowell contends in the July issue of Review of Policy Research. "Speed limits are far less important."

Research from Kansas State University earlier this year would seem to support Yowell's claim. Civil engineer Sunanda Dissanayake found four factors that were consistently most significant in contributing to fatalities in rural highway crashes:

  • Driving under the influence
  • Driving at higher than the posted speed limit
  • Not using a seat belt
  • Being ejected from the vehicle

Dissanayake also found that 75 percent of highway accidents occur in rural areas, largely because laws are more stringently enforced on urban highways.

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