New Mexico Route 501 is a very short state highway in New Mexico, United States of America. Its total length is only about . New Mexico Route 501's southwestern terminus is at New Mexico State Road 4 west of Los Alamos. It runs northeast into the town of Los Alamos, where it ends. It passes through the territory of Los Alamos National Laboratory (LANL), which is closed to the public (the public may drive through on Route 501). Guard posts are at either end of the LANL section of the highway, and motorists passing into (but not out of) LANL territory must pause at the posts and be waved through. Under most conditions, no inspections, etc., are performed at the guard posts, but heightened security postures at LANL may lead to more intrusive checks.