Over four million miles of roadway span the United States. A driver in southeastern Florida City, Florida could hop in her car and 50 hours later step out into northwestern Blaine, Washington 3,435 miles away. Despite her long journey, she would have a remarkably consistent drive. She would travel on 12-foot wide interstate lanes constructed of approved asphalts, aggregates, and finishes. She would view highways signs fabricated from specified microprismatic sheeting and retroreflective paints. She would obey a nearly uniform set of traffic laws. She would experience a system that allows widespread access by nearly every shape, size, and make of vehicle, from Mazdas to Maseratis, from semi-trailers to school buses, from tower ladder fire trucks to Harley Davidson Fat Boys.