What's up with your speed limits and not follwing em?

I had to recently drive through PA, did a trip from Virginia -> Allentown -> Honsdale -> NY

The back road speed limit signs were all over 25, 35 45... In weird places. The thing that gets me though is almost ALL of the locals just speed like crazy! I'm following the speed limit on the high way cruising along at 55. Getting passed by hicks going way way over the speed limit. Flying past me. (And tailgating... Think that is happening all over now-days...)

Is this common in PA, just fuck speed limits?