What was expanded by the US bicameral legislature by the Federal-Aid Highway Act of 1968?
Federal-Aid Highway Act of 1968:  815) is legislation enacted by the United States Congress and signed into law on August 24, 1968, which expanded the Interstate Highway System by 1500 mi ; 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. United States Congress: The United States Congress is the bicameral legislature of the federal government of the United States consisting of two chambers: the Senate and the House of Representatives.
Interstate Highway System