America's newest wonder is located in Mohave County Arizona. The Hoover Dam bridge, offically named the "Mike O'Callaghan - Pat Tillman Memorial Bridge" crosses the Colorado River, on the border between the US states of Arizona and Nevada.
The bridge carries vehicle traffic on US 93 across the river and diverted traffic off the badly congested Hoover Dam roadway. This bridge makes the trip from anywhere in Mohave County to Las Vegas a breeze. With this bridge there is 4 lane easy to drive highway on US 93 all the way to Las Vegas from the southern border of Mohave County, over 148 miles away.
The bridge is the second-highest bridge of any kind in the United States and 14th in the world. It is the highest and longest arched concrete bridge in the Western Hemisphere. It has the world's tallest concrete columns of their kind.
It is a composite steel and concrete arch 4 lane bridge of 1,500 feet, located downstream from the dam and is perched 890 feet above the Colorado River, wedged between rock cliffs that form Black Canyon.
Seven pairs of concrete columns rise from the slopes of the canyon's rock walls, and a series of eight more pairs are along the top the semicircular arch. The columns are made of stacked prefabricated concrete blocks and the arch was poured in place in midair.
1,200 skilled workers and 300 engineers worked on the project. The four-lane bridge opened on October 19, 2010.