U.S. Route 93 in Nevada portion of abandoned railroad right-of-way. A shopping center now sits where the original truck bypass alignment once ran. US 93 was realigned again on October 19, 2010, when the Mike O'Callaghan – Pat Tillman Memorial Bridge over the Black Canyon of the Colorado River opened to vehicular traffic. With that, the highway no longer passes over Hoover Dam, and the state-maintained portion of the replaced route was renamed as Hoover Dam Access Road (SR 172). In 2011, US 93 from Buchanan Boulevard to the Nevada terminus of the Hoover Dam Bypass was expanded to four through lanes with dedicated turn
Risks to the Glen Canyon Dam annually at Glen Canyon, and as Lake Powell is the farthest large reservoir upstream on the Colorado River mainstem, the sediment load is completely trapped in the reservoir as the Colorado discharges into it. This sediment is creating a steadily advancing "toe" of sediment, i.e. an underwater alluvial fan, that is advancing towards the dam. It is estimated that the sediment will reach the dam base in a minimum as low as eighty to one hundred years or as far as 500 to 700 years, although it will take much more time for the sediment deposited there to reach higher