The Federal-Aid Highway Act of 1968 (Public Law 90-495; 82 Stat. 815) is legislation enacted by the United States Congress and signed into law on August 24, 1968, which expanded the Interstate Highway System by 1,500 miles (2,400 km); provided funding for new interstate, primary, and secondary roads in the United States; explicitly applied the environmental protections of the Department of Transportation Act of 1966 to federal highway projects; and applied the Davis–Bacon Act to all highway construction funded by the federal government. It established three new programs: a National Bridge Inspection Program, funding and fair housing standards for those displaced by federally funded highway construction, and a traffic operations study program.