Sarah Laskow:

Dwight D. Eisenhower, contrary to popular belief, did not build the federal highway system for the sole purpose of evacuating cities in the event of an atomic war. But there was one key military endeavor that did influence Eisenhower’s support for giant, smoothly paved roads. In 1919 he traveled with the military in a motor convoy across the country, from D.C. to San Francisco, in “the largest aggregation of motor vehicles ever started on a trip of such length,” the New York Times reported.
 
 This was one of the first major cross-country road trips, and it planted the idea in the Eisenhower’s mind that the federal government could and should make improving U.S. highways a priority. Soon, driving from coast to coast would become mythologized as one of the key American experiences. But in 1919 it was a terrible, torturous endeavor.