Interstate 81 forms a major north -- south corridor through the state of Pennsylvania , serving the boroughs of Chambersburg and Carlisle , where it meets the Pennsylvania Turnpike ( I-76 ) but does not directly interchange with it ( motorists must use US 11 to connect ) .
Interstate 81 forms a major north -- south corridor through the state of Pennsylvania , serving the boroughs of Chambersburg and Carlisle , where it meets the Pennsylvania Turnpike . But I-81 does not directly interchange with it ( motorists must use US 11 to connect ) .