Hoover Dam the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with." Hoover Dam was recognized as a National Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981, and was designated a National Historic Landmark in 1985, cited for its engineering innovations. Other sources Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the
The Exploration of the Colorado River and Its Canyons The Exploration of the Colorado River and Its Canyons The Exploration of the Colorado River and Its Canyons by John Wesley Powell is a classic of American exploration literature. It is about the Powell Geographic Expedition of 1869 which was the first trip down the Colorado River by boat, including the first trip through the Grand Canyon. Powell's first written accounts of his exploration appeared in the January, February and March 1875 editions of "Scribner’s Monthly" as "The Canons of the Colorado". The Smithsonian published it in book form in 1875 under title "Report of the Exploration of the Colorado