120th

William "Pudge" Heffelfinger becomes the first professional football player (1892).

115th

The Latrobe Athletic Association football team becomes the first team to play a full season with only professional players (1897).

110th

A precursor to what would eventually become the Super Bowl called the World Series of Pro Football is played for the first time (1902).

90th

The American Professional Football Association changes its name to the National Football League (1922).

80th

The Washington Redskins franchise plays its first season. The team is founded in Boston and is called the Braves (1932).

80th

Official statistics are kept for the first time (1932).

80th

On December 18, 1932, the NFL has its first playoff game and first indoor game. Chicago's Wrigley Field is scheduled to host the game but a blizzard makes it impossible to play, and the game is moved indoors to Chicago Stadium.

[ Check out the 1932 NFL Indoor Championship ]

80th Season

The Pittsburgh Steelers franchise plays its first season. The team is called the Pirates (1933).

The Philadelphia Eagles franchise plays its first season (1933).

60th

The Pittsburgh Steelers are the last pro team to abandon the single-wing in favor of the T-formation (1952).

50th

The NFL reaches a single-network agreement with CBS for telecasting all regular-season games for $4.65 million annually (1962).

50th Season

The Pro Football Hall of Fame is established (1963).

The Chiefs franchise move to Kansas City (1963).

45th

The Green Bay Packers defeat the Dallas Cowboys 21-17 in the coldest NFL game on record: the 1967 NFL Championship dubbed forevermore as the "Ice Bowl."

[ More ... 1967 NFL Championship: The 'Ice Bowl' ]

On August 15, 1967, Denver defeats Detroit in a preseason game, 13-7, to notch the AFL's first win over an NFL team.

40th

The Miami Dolphins complete the NFL's only perfect championship season (1972).

[ More ... 1972 Dolphins: The Perfect Season ]

The "Immaculate Reception" touchdown was scored in an AFC Divisional playoff game by the Pittsburgh Steelers' Franco Harris on December 23, 1972.

[ More ... The 'Immaculate Reception' ]

30th

The inbounds lines are moved closer to the center of the field so that they are 23 yards, 1 foot, 9 inches from the sidelines (1972).

25th

The first two NFL games on ESPN produce the two highest-rated and most-watched sports programs in basic cable history (1987).

10th

The NFL kicks off on Thursday night for the first time in history (2002).

The Houston Texans franchise is founded (2002).