Thank you for taking the time to answer my question. While I am in Texas now (probably why I thought UT was the largest), I grew up right by Arizona State College, now University, and apparently the largest. We Phonecians never saw that coming! Three of the top ten in the Department of Education list are Florida Universities and none are in New York or California. That surprises me too. I don't know how far such lists would go back but I would guess that a late as WWI the largest universities were private - Harvard, Yale ...

Minnesota seems very misplaced here. I thought it was among the smallest of the Big 10. If I get a minute I'll see what I can find.

OK, I found one list that put them 4th, one at 11th and one at 14th. Part of it is they have a relatively huge graduate student population of 20K versus 31K. Looking at the undergrad numbers I get a list closer to what I was expecting:
1 University of Central Florida a[›] Orlando, Florida 45,398[1] 2 Ohio State University Columbus, Ohio 41,348[2] 3 Arizona State University a[›] Tempe, Arizona 41,256[3] 4 Rutgers University New Brunswick, New Jersey 38,902[4][clarification needed] 5 Texas A&M University a[›] College Station, Texas 38,810[5] 6 Pennsylvania State University University Park, Pennsylvania 38,630[6] 7 University of Texas at Austin a[›] Austin, Texas 38,168[7] 8 University of South Florida a[›] Tampa, Florida 36,595[8] 9 Michigan State University East Lansing, Michigan 36,489[9] 10 University of Florida a[›] Gainesville, Florida 33,628[10]