First live coverage of the Kentucky Derby:

1952
On May 3, 1952, the Kentucky Derby had its first live broadcast on CBS.
Source: Total Television, McNeil, 1/1/1900

 
   
  First network broadcast of an NFL Championship Game:

1951
On Dec. 23, 1951, the Dumont Network broadcast the first network coverage of the National Football League Championship Game.
Source: Total Television, McNeil, 1/1/1900

 
   
  Year first beauty pageant televised on a network:

1950
On Sept. 3, 1950, the Dumont Network televised the "Miss Television U.S.A. Contest", which won by Edie Adams.
Source: Total Television, McNeil, 1/1/1900

 
   
  Year the first telethon was broadcast on TV:

1949
On April 9, 1949, Milton Berle hosted the "Damon Runyon Memorial Fund", history's first telethon for charity.
Source: Total Television, McNeil, 1/1/1900