The Boston Game:
The Boston Game is thought to be the origins of American football, played by New England prep schools. In 1855, manufactured inflatable balls were introduced. These were much more regular in shape than the handmade balls of earlier times, making kicking and carrying more skillful. Two competing versions had evolved during this time; the "kicking game" which resembled soccer and the "running" or "carrying game" which resembled rugby union. A hybrid of the two, known as the "Boston game," was played by a group known as the Oneida Football Club. The club, considered by some historians as the first formal football club in the United States, was formed in 1861 by schoolboys who played the "Boston game" on Boston Common. They played mostly among themselves early on; though they organized a team of non-members to play a game in November, 1863, which the Oneidas won easily. The game caught the attention of the press, and the "Boston game" continued to grow throughout the 1860s

NFL:
Although the team has been in Foxborough since 1971, a site closer to the state of Rhode Island, the New England Patriots are still generally considered to be Boston's football team. The team was founded in 1960 as the Boston Patriots, charter members of the American Football League. In 1970, the team joined the National Football League, and moved to Foxboro Stadium in 1971.
While in Boston, the team played at Nickerson Field (at the time still known and configured as Braves Field), Fenway Park, Harvard Stadium, and BC's Alumni Stadium (although the historic core of the Harvard campus and most of the BC campus are outside of the city limits, both stadiums lie within the city). The team has won three Super Bowl titles (2002, 2004, 2005) since the 2001 season, and are the only team to go 16-0 in the regular season (2007).and currently is considered to be second in popularity only to the Red Sox. They share Gillette Stadium with the New England Revolution of Major League Soccer