The Alaskan Way Viaduct was originally built to carry a section of U.S. Route 99, the main north–south highway in Washington and along the U.S. West Coast. The highway previously used downtown streets, but rising automobile congestion in the 1920s sparked proposals for a limited-access bypass of Seattle. An elevated roadway, placed along the waterfront's Railroad Avenue (later renamed Alaskan Way), was recommended by several city engineers in the latter part of the decade. Plans for an elevated highway gained public support in the late 1930s and was approved for construction in 1947 using funds from the Federal-Aid Highway Act of 1944.