This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
Bicycles are prohibited on Interstate highways in Pennsylvania. 75 Pa.C.S. § 3511 prohibits pedalcycles and pedestrians on freeways and limited-access highways in Pennsylvania, including the entire Interstate system. PennDOT signs the prohibition at on-ramps; cyclists must use the parallel US and state-route network.
What this means in practice
Stick to surface streets, US routes, state highways, and dedicated paths. If your route in Pennsylvania appears to use an Interstate, plan a detour before you start.