At Michigan about 85% of the house have pledge classes of 40+ girls. The largest I ever heard of was Theta with 51 in a pledge class.
Ive heard one girl say that about her sorority when she was a soph that she barely knew the Juniors in her house and didnt know the Seniors at all. Then one girl told me that b/c they had a class of 51, initiation took 8 hours to get through. It got so tiring that the Seniors and some Juniors got up and left. I mean its sad that they barely know each other, but your only required to live in 1 or 2 years so when your a junior and senior your not really in on everything cuz your living out the house. There could still be a strong sisterhood with 200+ girls (as Ive seen on my campus) it just depends on how active people want to be in their house. Small and big have its advantages and disadvantages

The most Ive heard about fraternities is Beta at my school. I think its said they have 100+ living in their house and 200 who dont live in. Dont know, but they do have a huge chapter.