When my university's football team plays a home game, there are usually 110,000 people in attendance. The streak of 100,000+ people for each home game goes back to 1975.
In terms of attendance, the top college teams beat even professional teams. The 13 largest stadiums in the US are all for college football [1]. You have to go all the way to number 14 before you get to a stadium used for professional sports.
Some of that is due to being older stadiums, though. U.S. professional stadiums used to have more capacity, because they were just rows and rows of bleachers. The trend in the past few decades in professional sports has been towards more of the space being used for lower-density "premium" seating like skyboxes and fewer bleachers, reducing the seat count. College sports usually have less funding for new stadiums though, and their market is a bit different (more regular fans paying out of pocket, less demand for corporate skyboxes). Hence you have something like the LA Coliseum, capacity 93,000, used by USC's college football team, but considered an "obsolete" stadium by the NFL and MLB, who used to use it but moved out.
