Raising speed limits does not cause a significant increase in fatalities, a new study says. The study, to be published in the July issue of Review of Policy Research by Blackwell Publishing, examined changes in speed limit laws over the past few decades. Analysis of the highway deaths per mile driven after the 1974 nationalization of the maximum highway speed shows an initial greater decline in deaths, though that spike was followed by a re-emergence of the same decreasing trend of deaths. Speed limits were formed in the 1970s to improve fuel efficiency during the gasoline shortage. In the 1980s the focus shifted to public safety, though in 1987 Congress allowed states to post 65 MPH daytime limits on rural interstates. In 1995 Congress returned all speed limit authority back to the states. At that time the Department of Transportation predicted an additional 6,400 deaths every year as a result.That never happened, says the study’s author, political scientist Robert Yowell of the Stephen F. Austin State University in Texas. In fact, from 1968 to 1991, the fatality rate per 100 million miles declined by 63.2 percent.Yowell said that technical progress in car manufacturing, increased seatbelt use, higher drinking ages and better road maintenance had greater effects on the fatality rate.These results come as several states including Texas, Iowa and Indiana are raising their maximum allowable speeds. The top legal speed in Texas will rise as high as 80 miles per hour following legislation signed into law this month.