Black and white image of the group of men who witnessed the pouring of the first concrete in Hoover Dam proper. From left to right: H. J. Lawler, Director of Six Companies, Inc.; Walker R. Young, Construction Engineer, U.S. Bureau of Reclamation; Frank T. Crowe, General Superintendent, Six Companies, Inc.; C. A. Shea, Director of Construction, Six Companies, Inc. W. A. Bechtel, President, Six Companies, Inc.; R. F. Walter, Chief Engineer, U.S. Bureau of Reclamation; Theodore A. Walters, First Assistant Secretary of the Interior ; Ed Clark & C. P. Squires, members of the original Colorado River Commission. Note: Boulder Dam was officially renamed Hoover Dam in 1947.