Pennsylvania county map

How Pennsylvania’s counties are laid out

Pennsylvania’s 67 counties cover 46,054 square miles, an average of just under 700 square miles each. The three original counties — Philadelphia, Bucks and Chester — were established by William Penn in 1682 along the Delaware River, and every other county descends from them. Lancaster (1729), York (1749), Cumberland (1750), Berks and Northampton (1752) and Bedford (1771) mark the westward spread of settlement across the Susquehanna and into the ridge-and-valley country. The counties west of the Alleghenies date largely from 1788–1804, after the frontier opened following the Revolution, and the north-central “Northern Tier” counties of Potter, Tioga, McKean and Elk were organised last, in 1804–1843, as the lumber industry pushed into the plateau.

County names show three layers of history: English places and Penn associates (Bucks, Chester, Lancaster, York, Northampton), Revolutionary and early-republic figures (Washington, Greene, Franklin, Fayette, Mifflin, Wayne, Montgomery, Warren) and Native American or river names (Lackawanna, Lehigh, Lycoming, Juniata, Susquehanna, Wyoming). Several county seats are not the largest town in their county: Doylestown serves Bucks, Media serves Delaware County, Norristown serves Montgomery and Bellefonte serves Centre, whose biggest community is State College.

Philadelphia is a consolidated city-county: the city and county boundaries have been identical since the Act of Consolidation of 1854, and the city government does the county’s work. Pennsylvania has no independent cities. Most counties are run by three elected commissioners; several of the largest, including Philadelphia, Allegheny and the Philadelphia suburban counties, have adopted home-rule charters with councils and executives.

All 67 counties of Pennsylvania

Five county facts

• Largest by area: Lycoming County, seat Williamsport, about 1,240 square miles of the West Branch Susquehanna valley and the plateau north of it. Potter, Clearfield and Centre counties are the next largest, all above 1,100 square miles.
• Smallest by area: Montour County, seat Danville, about 130 square miles on the North Branch Susquehanna — slightly smaller than the City and County of Philadelphia, which is about 135 square miles of land.
• Most populous: Philadelphia, with about 1.6 million people in 2020. Allegheny County (Pittsburgh) is second at about 1.25 million, followed by the Philadelphia suburbs of Montgomery, Bucks and Delaware counties, each above 575,000.
• Least populous: Cameron County, seat Emporium, in the Allegheny Plateau of the north-central region, with about 4,500 people. Forest, Sullivan and Fulton counties are the other three below 15,000.
• Oldest and newest: Philadelphia, Bucks and Chester counties date from 1682, the founding year of the colony. Lackawanna County (Scranton), separated from Luzerne in 1878, is the newest — the map has been unchanged for nearly 150 years. Pennsylvania has one consolidated city-county (Philadelphia) and no independent cities.

Reading the map

Press Streets and zoom in on the highlighted state to see county lines. In the south-east the counties are small and crowded: the five counties of the Philadelphia area hold nearly a third of the state’s population in well under a tenth of its land. Moving north-west the counties grow larger and emptier across the folded ridges of the Appalachians; the straight-sided counties of the Northern Tier along the New York line and the triangle of Erie County on the lake shore are the most regular in shape. The Susquehanna and its branches thread through the centre of the state, and Harrisburg, the capital, is the seat of Dauphin County on its east bank. The Mason–Dixon line forms the straight southern boundary of the eight counties from Greene to Chester. The whole state keeps Eastern Time.

Related maps

• Pennsylvania map — cities, borders and geography.
• Blank Pennsylvania map and printable Pennsylvania map.
• Harrisburg, the state capital, in Dauphin County; Philadelphia and Pittsburgh.
• Neighbouring county maps: New York, New Jersey, Delaware, Maryland, West Virginia, Ohio.
• Middle Atlantic states · the Northeast · Eastern Time Zone.
• Geography: Appalachian Mountains, Ohio River, Great Lakes.
• All US county maps.