PENNSYLVANIA
Browse Pennsylvania’s County Histories
Click on a county to see its history. Jurisdictions with resources have a green border. Those displayed in gray are counties that are no longer active under their original designation; to delve deeper into the various reasons for their change, please visit our Understanding Extinct Counties page.
ADAMS COUNTY
ALLEGHENY COUNTY
ARMSTRONG COUNTY
BEAVER COUNTY
BEDFORD COUNTY
BERKS COUNTY
BLAIR COUNTY
BRADFORD COUNTY
(FORMERLY ONTARIO COUNTY) BUCKS COUNTY BUTLER COUNTY CAMBRIA COUNTY CAMERON COUNTY CARBON COUNTY CENTRE COUNTY CHESTER COUNTY CLARION COUNTY CLEARFIELD COUNTY CLINTON COUNTY COLUMBIA COUNTY CRAWFORD COUNTY CUMBERLAND COUNTY DAUPHIN COUNTY DELAWARE COUNTY ELK COUNTY ERIE COUNTY FAYETTE COUNTY FOREST COUNTY FRANKLIN COUNTY FULTON COUNTY GREENE COUNTY HUNTINGDON COUNTY INDIANA COUNTY JEFFERSON COUNTY JUNIATA COUNTY LACKAWANNA COUNTY LANCASTER COUNTY LAWRENCE COUNTY LEBANON COUNTY LEHIGH COUNTY LUZERNE COUNTY LYCOMING COUNTY MCKEAN COUNTY MERCER COUNTY MIFFLIN COUNTY MONROE COUNTY MONTGOMERY COUNTY MONTOUR COUNTY NORTHAMPTON COUNTY NORTHUMBERLAND COUNTY PERRY COUNTY PHILADELPHIA COUNTY PIKE COUNTY POTTER COUNTY SCHUYLKILL COUNTY SNYDER COUNTY SOMERSET COUNTY SULLIVAN COUNTY SUSQUEHANNA COUNTY TIOGA COUNTY UNION COUNTY VENANGO COUNTY WARREN COUNTY WASHINGTON COUNTY WAYNE COUNTY WESTMORELAND COUNTY WYOMING COUNTY YORK COUNTY
(FORMERLY ONTARIO COUNTY) BUCKS COUNTY BUTLER COUNTY CAMBRIA COUNTY CAMERON COUNTY CARBON COUNTY CENTRE COUNTY CHESTER COUNTY CLARION COUNTY CLEARFIELD COUNTY CLINTON COUNTY COLUMBIA COUNTY CRAWFORD COUNTY CUMBERLAND COUNTY DAUPHIN COUNTY DELAWARE COUNTY ELK COUNTY ERIE COUNTY FAYETTE COUNTY FOREST COUNTY FRANKLIN COUNTY FULTON COUNTY GREENE COUNTY HUNTINGDON COUNTY INDIANA COUNTY JEFFERSON COUNTY JUNIATA COUNTY LACKAWANNA COUNTY LANCASTER COUNTY LAWRENCE COUNTY LEBANON COUNTY LEHIGH COUNTY LUZERNE COUNTY LYCOMING COUNTY MCKEAN COUNTY MERCER COUNTY MIFFLIN COUNTY MONROE COUNTY MONTGOMERY COUNTY MONTOUR COUNTY NORTHAMPTON COUNTY NORTHUMBERLAND COUNTY PERRY COUNTY PHILADELPHIA COUNTY PIKE COUNTY POTTER COUNTY SCHUYLKILL COUNTY SNYDER COUNTY SOMERSET COUNTY SULLIVAN COUNTY SUSQUEHANNA COUNTY TIOGA COUNTY UNION COUNTY VENANGO COUNTY WARREN COUNTY WASHINGTON COUNTY WAYNE COUNTY WESTMORELAND COUNTY WYOMING COUNTY YORK COUNTY