Currently, there are 4.12 million miles of road in the United States, according to the Federal Highway Administration, including Alaska and Hawaii. The core of the nation’s highway system is the 47,575 miles of Interstate Highways, which comprise just over 1 percent of highway mileage but carry one-quarter of all highway traffic. The Interstates plus another 179,650 miles of major roads comprise the National Highway System, which carries most of the highway freight and traffic in the U.S.
Most of the roads in the U.S., 2.94 million miles, are located in rural areas, with the remaining 1.18 million miles located in urban areas. Local governments are responsible for maintaining and improving 3.18 million miles of road or 77.3 percent of the total. State highway agencies are responsible for over 780 thousand miles of road, or 19.0 percent. The federal government is responsible for only 150 thousand miles of road or 3.7 percent, largely roads in national parks, military bases and Indian reservations.
Of the 4.07 million miles of road, about 2.68 million miles are paved, which includes most roads in urban areas. However, 1.39 million miles or more than one-third of all road miles in the U.S. are still unpaved gravel or dirt roads. These are largely local roads or minor collectors in rural areas of the country. (Source: Highway Statistics 2013 Table HM-20, HM-10, HM-12, HM-15, VM-202)