This is just a misconception people from abroad have. Almost all the teen dramas on American television have sexually active teenage characters. It's really blown out of proportion, and it's mostly a Christian thing. Although, our culture loves to demonize promiscuity, which I personally I don't understand, and I've lived in the States since I was two years of age.
Your college question was on point, but this virginity issue is largely a farce, even among the fundamentalist Christians in the US. All of this stuff about purity rings etc. is nonsense. Vast majority of Americans have sex before marriage. Your question would be better addressed towards some Muslim country where perhaps the women, if not the men, actually practice this virginity until marriage. Here, even if the girl is protecting her "virginity" to not become pregnant, avoid disease, religious reasons, etc. she may be giving out handjobs and more.