Interstate 40 (I-40) is a major Interstate Highway running through the south-central portion of the United States generally north of Interstate 10 and Interstate 20 but south of Interstate 70. The western end is at Interstate 15 in Barstow, California; its eastern end is at a concurrency of U.S. Route 117 and North Carolina Highway 132 in Wilmington, North Carolina. Much of the western part of I-40, from Oklahoma City to Barstow, parallels or overlays the historic U.S.