* March 18 – The Tri-State Tornado, the deadliest in U.S. history, rampaged through Missouri, Illinois, and Indiana, killing 695 people and injuring 2,027.
* 30. december - astronom Edwin Powell Hubble oznani odkritje, da je Andromeda pravzaprav galaksija, torej je naša galaksija samo ena od mnogih v Vesolju.