HAHAHAHAHAHA! PA uses both. TRxxx is town road, CRxxx is county road, SRxxx is state road. Keeps things a little better organized. Us rednecks stay on the TR'*. Statey'* got to many county contracts around here to patrol and pay them no attention.
Western Michiganders have a weird thing were they name roads how many miles away from a bigger town the road is. So you have 1 Mile Road, then 2 Mile road, then 3 miles road. And on. And on. And freaking on as you go out into the Country.