In the State of California, Interstate 40 (I-40) begins on the west at its interchange with Interstate 15 in Barstow. Sometimes called the Needles Freeway, it is a major east—west highway of the Interstate Highway System that goes all the way to Wilmington, North Carolina. I-40 goes east from Barstow across the Mojave Desert in San Bernardino County past the Clipper Mountains to Needles, before it crosses over the Colorado River into Arizona east of Needles.