In Black Canyon spanning the Colorado River between Arizona and Nevada, about 30 miles southeast of Las Vegas, Nevada. It is 726.4 feet from foundation rock to the roadway on the crest of the dam. The towers and ornaments on the parapet rise 40 feet above the crest. More than 6,600,000 tons. A concrete arch-gravity type, in which the water load is carried by both gravity action and horizontal arch action. 45,000 pounds per square foot. Three and one-quarter million cubic yards. There are 4,360,000 cubic yards of concrete in the dam, powerplant and appurtenant works.