There are enough roads in the U.S. to stretch from the earth to the moon 8 times!
The U.S. interstate system has a total length of over 46,000 miles, but that is only a small fraction of the total number of roads in the country. Transportation engineers have helped to build almost 4 million miles of road in the United States. That's enough to stretch from the earth to the moon 8 times. And the concrete used to construct the Interstate System alone could build a wall nine feet thick and 50 feet high around the world’s equator.
Brief history of the Lincoln Highway, one of the first in the country.
All you want to know about the U.S. Interstate Highways