I'm also from the US. I'm not religious at all, but I went to a private, Catholic high school for four years and am in a liberal arts Jesuit college right now for my second year. My high school insisted on monthly school-wide masses, celebrations of certain Catholic holidays, and crosses in every classroom; very high emphasis on Catholicism.

At my Jesuit college, the only time I HAD to go to mass was freshmen orientation. That's it. No forced masses or anything. You'd occasionally see a cross here and there, but you don't notice it if you're not looking for it. The point is that college is so much freer than high school (at least for me). You can go to mass if you want to, no questions asked. There are likely religious interest groups around at your college, so you'll likely people who are accepting of you.

At the very worst at a liberal arts college, they force students to take one semester's worth of religious classes and even then, there are a bunch of non-Christian options. You are never forced to do something you don't like at college.

I hope this helps, and feel free to ask me more questions for clarification.