I grew up in a US college town. As a high school student (or any state resident I think) I could just go in and get a library card, and check out books. Anyone can get into the library, even without a card. Some caveats, it's a public university, and the main library was wide open, but there are also several small libraries strewn about campus (engineering, geology, chemistry, etc) that you may or may not have to swipe to get into. I think once you get a card, you can get in though, as I remember getting a card to getin into the earth sciences library for a high school project.