NFL football teams field 11 players on each side of the ball, except for when you are at a Seattle Seahawks game. Seattle loves the Seahawks and the rabid Seattle fans are known as the “12th Man“, meaning opposing teams have an extra 12th player to contend with – the fans. The 12th Man fans are often mentioned as the loudest in the NFL. When you drive around Seattle during football season, you will see many public buildings with a blue and white “12” flag hoisted above. This is the city showing support for their team.
The Seahawks regular season runs from September-January, and hopefully longer if they make it into the playoffs. Here is a link to the Seahawks season schedule.