In my experience, you make more friends at a small school than a large school. I started my college career at a very large school where I had a few close friends who lived on my dorm. I met lots of people, but because the school was so large, I never saw many of them more than once. I finished at a small school where I had many friends because I saw people everywhere and got to know them better.
Having attended nothing but small schools in my youth I can affirm that you do not make more friends in smaller schools. If anything, the smaller school setting made it easier for people to classify and segregate themselves and further develop cliques in order to exclude those people they were not interested in being around.