- 
  
  The development of the first atomic bomb is signed into agreement between the Prime minister of Great Britain, Winston Churchill, and FDR in Hyde park, NY.
- 
  
  The first nuclear chain is produced at the University of Chicago. Creating fission of the Uranium U-235.
- 
  
  Ralph Buche appointed 1st African American official into the US State Department.
- 
  
  G.I. Bill of rights is signed into law, providing benefits to veterans.
- 
  
  FDR sworn in for an unprecedented 4th term as the U.S. President.
- 
  
  President Franklin D. Roosevelt suddenly dies. Vice President Harry S. Truman assumes the presidency following FDR's death.
- 
  
  Truman gives the greenlight for the use of the atomic bomb with the bombing of Hiroshima. 3 days later the second bomb is dropped on Nagasaki.
- 
  
  President Truman establishes the Presidents committee on civil rights to investigate the status of civil rights in the Unites states.
- 
  
  Truman signs the Marshall plan which authorizes 15 billion in aid for 16 countries.
- 
  
  The 22nd Amendment to the U.S. limiting presidents to two terms is ratified.
- 
  
  Marshall plan expires after distributing more than 13.3 billion USD in foreign aid to rebuild Europe.
- 
  
  President Truman announces the United States has developed a hydrogen bomb.
- 
  
  Dwight D. Eisenhower is sworn into office as the 34th President of the U.S.