Cowboys - In terms of geographic reach, the Cowboys really are America's Team. Their fan empire stretches from Kern County, California to central Florida to southern Virginia to northern Montana.
Steelers - Another large fan empire that claims almost all of Pennsylvania and stretches across Appalachia and both Carolinas.
Packers - A fan base that includes lots of countries across the northern US, all the way to Oregon. (They also cover most of Alaska)
Bears - Most of Illinois is closer to St. Louis than Chicago, but the Bears fan base covers the whole state.
Saints - Their fan base covers all of Louisiana, Mississippi, and Alabama, at the expense of the Texans, Titans, and Falcons respectively.
Dolphins - Their fan base covers many Florida counties that are closer to Tampa Bay or Jacksonville.
Giants - Despite sharing a stadium with the Jets, they claim virtually all of the surrounding territory, with the exception of Nassau County.