Nevada State Route 172

State Route 172 (SR 172) is a state highway in Clark County, Nevada. The route provides access to Hoover Dam from Interstate 11 (I-11)/U.S. Route 93 (US 93)/U.S. Route 93 Business.

Route description
State Route 172 begins on Gold Strike Pass Road and Goldstrike Canyon Road, at an interchange with I-11/US 93/US 93 Bus. approximately 5 mi northeast of downtown Boulder City. Proceeding northward for only a few feet, it turns right onto the old Nevada Highway, the original route of US 93. From there, the route travels eastward, following the curvy mountainside over Rough Summit headed toward Hoover Dam. Shortly after passing the turnoff for the Lakeview scenic viewpoint, the SR 172 designation ends 1.61 mi west of the Arizona state line, just prior to a security checkpoint at the boundary with the Bureau of Reclamation's Hoover Dam Reservation. While the state highway designation ends at this point, the Hoover Dam Access Road continues eastward, passing the Mike O'Callaghan – Pat Tillman Memorial Bridge Plaza, the Hoover Dam visitor center, and then crosses the dam itself into Arizona. However, it only runs a short distance in that state before looping through a new parking area at a helipad to return the way it came, the original road past that point being blocked off to prevent all but dam personnel from continuing further south.

History
SR 172 was originally part of US 93. US 93 was rerouted onto the Hoover Dam Bypass when construction was completed in October 2010, and the new state highway was designated over the old route.