WikipediaIn the National Football League (NFL), a tied game occurs when a regular season game ends with both teams having an equal score after one ten minute overtime period. Ties have counted as a half-win and half-loss in league standings since 1972; before that, ties were not counted in the standings at all. NFL teams rarely play for ties. In general, tied games in the NFL are frowned upon by both teams and fans. Because tied games are rare, some players have not known they were allowed in the NFL, such as former Philadelphia Eagles quarterback Donovan McNabb, who said after a tie game against the Cincinnati Bengals that he did not know a tie was a possible result.Tie games were frequent in the NFL from its inaugural season in 1920 through 1973, when the league did not have overtime during the regular season. During this period, the NFL had a total of 258 tied games. Only three seasons (1934, 1950, 1952) went without a tied game, while five seasons (1920, 1923, 1926, 1929, 1932) had at least ten ties. The most ties, 17, occurred in the 1920 season.Ties became uncommon after a 1974 rule change added one sudden death overtime period (15 minutes) to regular-season and preseason...
https://en.wikipedia.org/wiki/List_of_NFL_tied_games