Where in eastern PA can I legally ride my dirt bike? (trails/parks)?

So I've been riding my 1979 Honda XL for a few months now (first bike) and I'm really interested in riding offroad now. The only place I can ride dirt right now is at a construction site down the street. Where are there any trails or parks that I can legally ride at in eastern PA or within a reasonable distance of West Chester, PA.

(or any places that aren't so legal but fun to ride at… Haha)

Try riderplanet.com. I use it for 90% of my trail riding needs.