After the Interstate Highway System was signed into law in 1956, the Midland Trail portion of US 60, from Louisville east to the Hampton Roads area, was bypassed by Interstate 64. From Phoenix west to Los Angeles, Interstate 10 paralleled and, for the most part, replaced US 60. I-10 and I-64 were mostly completed by the late 1970s, though part of Interstate 64 in West Virginia, built on a new alignment east from Beckley, did not bypass the old winding US 60 until July 15, 1988. California decommissioned its portion of US 60 in 1972; most was replaced by I-10, while the independent piece in the Los Angeles area became State Route 60. In 1982, the portion overlapping I-10 in western Arizona was removed. US 60 between Phoenix and Louisville remains a major regional corridor in most places, and is not paralleled by an Interstate for any significant length.