U.S. Route 138, commissioned in 1926, is an east–west U.S. Highway in Colorado and Nebraska that runs predominantly northeast to southwest paralleling the South Platte River and Interstate 76. Like all spurs of the former U.S. Route 66 and U.S. Route 99, U.S. Route 138 is an orphan route. U.S. Route 38 was commissioned in 1926, but U.S. Route 6 was extended over it to Long Beach, California (but was truncated to Bishop in 1964). Therefore, U.S. 138 still meets its former parent route.