AbstractThe national 55 mile‐per‐hour speed limit was in effect from 1974 to 1987, and over the years many analysts have attempted to measure and compare its costs (enforcement and travel time) and benefits (safety and fuel economy). In 1984 a committee of the National Research Council completed a major study of the speed limit. The following article completes the committee's calculations; summarizes the results in units of money, lives, and travel time; and divides these effects between rural interstates and all other roads. Over a range of plausible dollar values for extra travel time, the cost of saving a life is estimated to be much higher on rural interstates than on other affected roads—and higher than the cost of saving a life by other highway safety measures as well. Hence, proponents of higher speed limits on the rural interstates have a strong case in the debate, which continues in the state legisla