January 20 - The Central Intelligence Group, later to become the Central Intelligence Agency, is established by President Truman.
February 16 - The first helicopter is commercially designed in Bridgeport, Connecticut.
March 5 - Churchill makes a speech in the U.S. warning Western nations to beware of the U.S.S.R. and the Iron Curtain across Europe.
August 1 - The McMahon Act in the U.S. establishes the Atomic Energy Commission.
September 30 - The International Military Tribunal ends in Nuremberg, Germany. Twenty-two top officials in Hitler's Nazi regime are found to be guilty of war crimes, and eleven of them are sentenced to death.
October 28 - The Atomic Energy Commission is created.
November 13 - The first artificial snow is produced by Vincent Schaefer at Mount Greylock, Massachusetts.