Hearings Before the Fiscal Affairs Subcommittee of the Committee on the District of Columbia, United States Senate, Eighty-fifth Congress, First Session, on S. 944, Providing for a Tunnel Across the Potomac River in the Vicinity of Constitution Avenue and S. 1707, Providing for a Bridge Across the Potomac River in the Vicinity of Constitution Avenue. April 11, 17, and 25, 1957