Two American professional football teams have had perfect seasons, these were the 1948 Cleveland Browns and the 1972 Miami Dolphins.
22324 undefeated teams
There have been over 100 undefeated football teams in NCAA history. The most recent was the 2013 champion, Florida State (14-0).
17 teams have gone undefeated in the regular season and of those only 1 (Indiana in 1976) has gone on to win the National Championship.
There are no more undefeated teams left in the National Football League during the 2010-2011 season
Only one I think...
One, the 1972 Miami Dolphins.
1972 Miami Dolphins and 2007 New England Patriots.
the Colts have never gone undefeated,,,only two teams have.1972 Miami Dolphins (14-0)2007 New England Patriots (16-0)