The State of Our Interstates

Our nation’s economy depends on its roads for low-cost movement of goods and people, so their deterioration could have a substantial impact on macroeconomic performance. The authors measure the state of our interstate highway system, using data on road deterioration collected from state highway agencies by the U.S. Department of Transportation’s Federal Highway Administration (FHA). For each year from 1980 through 2006, these data indicate the average daily vehicle traffic and surface roughness of each interstate highway segment in the country. Since the mid-1990s, our nation’s interstate highways have become indisputably smoother and less deteriorated. Indeed, the surface of the median interstate highway mile is suitable for superhighway speeds not typically permitted in the United States. Thus, investments to increase further the smoothness of interstate highways without targeting them to the roughest areas are unlikely to yield a substantial direct benefit.