[ghaff]

A lot of well-known private colleges/universities were single-sex, albeit sometimes with exchange programs/affiliates, until relatively recently and there remain significant single-sex, especially all-women, colleges today. Dartmouth, another Ivy, didn't go co-ed until 1972.

A lot of universities, especially those more focused on science and engineering, that were technically co-ed--even from their start in the 1800s--also didn't have a lot of women for a long time. The percentage of women at MIT was still under 20% in the late seventies.