I grew up in Pennsylvania. Bucks county has lots of historical stuff if you're into that. There's lots of covered bridges if you google it. Also, there's the house of author Pearl S. Buck. A famous tile factory, the Mercer Museum. Anyway, if you're in the area, there's lots of this kind of stuff.
Also, when driving through the state on Rt. I80 I always see signs for interesting things like Crystal Cave. I have always wanted to drive that when I have time to just pull over at anything interesting.