As of 2006 there were 46,876 miles of roadway in the Dwight D. Eisenhowere National System of Interstate and Defense Highways.
about 50,000 miles
According to the most recent (2007) data available, there are 2,615,870 miles (4,209,835 km) of paved roads in the U.S.
79,696
1000000000000000