- June (21): Maury Island Incident
- July: Roswell Incident
- July 26: National Security Act of 1947 signed by CIA established
- September 9, 1947 — First computer bug found in relay 70, panel F of the Mark II Aiken Relay Calculator
- December 1 — Aleister Crowley died
- December 30 — Project Sign founded to officially investigate UFOs