Just a Wikipedia dump that ran through my head today, re: the name "Big Ten".
Here were the stadium capacities for the Big Ten and ACC in 1970
Illinois - 71,227
Indiana - 52,324
Iowa - 60,160
Michigan - 101,001
Michigan State - 76,000
Minnesota - 56,652
Northwestern - 55,000
Ohio State - 81,455
Purdue - 69,200
Wisconsin - 77,280
Clemson - 43,451
Duke - 44,000
Maryland - 34,680
North Carolina - 48,000
NC State - 41,000
South Carolina - 42,238
Virginia - 23,848
Wake Forest - 31,500
Here were the stadium capacities for the Big Ten and ACC in 1970
Illinois - 71,227
Indiana - 52,324
Iowa - 60,160
Michigan - 101,001
Michigan State - 76,000
Minnesota - 56,652
Northwestern - 55,000
Ohio State - 81,455
Purdue - 69,200
Wisconsin - 77,280
Clemson - 43,451
Duke - 44,000
Maryland - 34,680
North Carolina - 48,000
NC State - 41,000
South Carolina - 42,238
Virginia - 23,848
Wake Forest - 31,500