Dam height is 726.4 feet, which makes it the second highest dam in the United States behind the Grand Coulee Dam based in Washington state. Dam length is 1,244 feet. The dam spans Black Canyon and the Colorado River and connects the states of Nevada and Arizona. Dam thickness is 660 feet. In addition to holding back the river, the structure features a two-lane road, which, before 2001, was frequently used by trucks to haul freight.