Collegiate teams are divided into Division 1 and 2. As opposed to many sports, the divisions are based almost entirely on school size. Any school with more than 15000 full time students must compete in Division 1. Smaller schools compete by default in Division 2, but at the start of the academic year may opt to race in Division 1.
In practice the divisions primarily matter for nationals qualifying and competition. However, ECCC road races typically divide Men's C and D into Division 1 and 2 fields in order to safely accommodate the large number of racers.
Full-time enrollment numbers are taken as those published in the U.S. Department of Education's Integrated Postsecondary Education Data System (IPEDS) database.
Further information is available in the USAC Collegiate rulebook [7F].