Alcatraz prison closed on March 21, 1963. The main reasons for its closure were its high operating costs, the structural deterioration of the facility due to saltwater exposure, and concerns about security following a famous escape in 1962. The prison was much more expensive to run than other federal prisons, costing about three times more per inmate per day. Additionally, since the island had no fresh water source, nearly one million gallons of water had to be shipped in weekly. The 1962 escape of three inmates who were never found raised concerns about the prison's vulnerability to further escape attempts. Repair costs were estimated to be very high, and the government decided it was more economical to build a new prison elsewhere than to continue operating and maintaining Alcatraz.