The federal government provides financial assistance to the state to help build and maintain highways because many of the state's roads also serve a national purpose. This does not make them federal roads. They are state roads. The only federal roads in South Carolina are found on military bases and other such facilities.
The federal funding that South Carolina receives can only be used for a few specific purposes. About half of the state-owned highway system is eligible for federal assistance; the rest of the roads must be maintained and improved with 100% state dollars.
Each state is required to "match" federal highway funds with state or local funds. The match ratio is generally 80% Federal and 20% State. That means that SCDOT pays the entire cost and is reimbursed 80% by USDOT.
Our total federal-aid program, including match, now stands at about $740 million per year. This is about $40 million below the FY '12 level. Most of the federal program is used for Interstate maintenance, bridge replacements, primary route maintenance, and the COG/MPO "Guideshare" Program.
Congress will enact a new Transportation Authorization bill in 2014. Until then, federal funding levels are expected to remain depressed.