Carol pointed me to this fascinating site which details some of America's decaying, abandoned amusement parks. I've actually been to Glen Echo Park (which isn't really abandoned) and we used to drive by Prehistoric Forest on our way to and from Ann Arbor, Michigan.
Really fascinating, melancholy stuff.
The comments mention an infamous abandoned park that's not listed, Action Park. This pic shows just how insane Action Park really was. (Image from Wikipedia).
Who the heck would build something so insane?!? Let alone, ride it.