While the Big Ten had the two top schools in terms of home attendance, there was no question which conference dominated overall. The SEC averaged 75,674 fans per game in 2013, which beat the Big Ten by more than 5,000 fans. No other conference topped 60,000 per game. In terms of raw attendance, the SEC drew over 7.5 million—roughly one out of every five people who attended a college football game last season; the Big Ten drew about 6.1 million; the ACC, about 4.8 million; the Pac-12, about 4.3 million; and the Big 12, about 3.9 million.
The attendance numbers certainly illustrate the vast chasm between the various tiers of college football. Consider the SEC's average attendance of roughly 75,000 per game with the Mid-American Conference, which averaged the lowest total in FBS with 16,739 fans per game. And as low as the MAC average appears next to the SEC, it still beats every other division of college football. The top finishing conference in the Football Championship Subdivision averaged just over 12,000 fans per game; in Division II, it drops to roughly 6,600 per game; and in the "pure" amateur football of Division III, it's roughly 3,300 per game. (If you're looking for the "Mr. Irrelevant" of college football attendance, it's likely Minnesota's Martin Luther College, a Division III school that drew 333 fans per game last year.)