Clark County designated the road Las Vegas Boulevard in 1959. It followed the course of the old Arrowhead Highway, the first all-weather road to connect Los Angeles with Salt Lake City, passing through Las Vegas en route. In 1926 the Arrowhead Highway was renamed U.S. 91. "It was only called the L.A. highway for convenience," says Michael Green of the University of Nevada-Las Vegas history department. It’s also been known as Salt Lake Highway and State Route 6. At one time, it was even split into U.S. 466 (from Fremont Street southward) and U.S. 93, from Fremont Street heading north.
That’s a lot of names for one road, no matter how illustrious. Anyway, the Boulevard enjoyed a schizoid existence as both U.S. 91 and Las Vegas Boulevard for over 15 years. It ceased to be U.S. 91 in 1974, when I-15 was completed. As for the South Fifth Street designation, that would only have applied to the portion of the road within Las Vegas city limits, particularly when it deviates from the Fifth Street route as it crosses into North Las Vegas. But Las Vegas Boulevard has been the prevailing nomenclature for nearly 60 years now.
