Alcatraz closed on 21 March 1963, after 29 years. The popular explanation is the 1962 escape. The real one is arithmetic.
1. Cost
Everything came by boat — food, fuel, supplies and roughly a million gallons of fresh water a week. Per-inmate operating costs ran several times higher than mainland federal prisons.
2. Deterioration
Decades of salt air had corroded reinforcing steel and plumbing throughout the cellhouse. Restoration estimates ran into millions of 1960s dollars, before running costs.
3. Policy
Federal corrections was shifting toward rehabilitation and integrated facilities. A punitive island fortress no longer fitted the direction of travel; the new penitentiary at Marion, Illinois, absorbed the role.
4. The 1962 escape
It did not cause the closure, but it undercut the prison's central claim — that Alcatraz was inescapable — at exactly the moment budget decisions were being made. See Frank Morris Alcatraz.
What happened next
The island sat empty until the Native American occupation of 1969–1971, then joined Golden Gate National Recreation Area in 1972 and opened to visitors in 1973 — the story continues on Alcatraz prison history.
Frequently asked questions
When did Alcatraz close?
On 21 March 1963, when the last 27 inmates were transferred off the island.
Did the 1962 escape close Alcatraz?
No. Cost and physical deterioration drove the decision, though the escape damaged the prison's reputation as the closure was being weighed.