County
| FIPS Code
[1] | County seat
[2] | Established
[2] | Origin
| Etymology
[3] | Population
[2] | Area
[2] | Map
|
| Adams County | 001 | Gettysburg | 1800 | Parts of York County. | John Adams | &0000000000091292.00000091,292 | &0000000000000522.000000522 sq mi
(&0000000000001352.0000001,352 km2) |  |
| Allegheny County | 003 | Pittsburgh | 1788 | Parts of Washington and Westmoreland Counties. | Lenape word, of uncertain meaning, for the Allegheny River | &0000000001281666.0000001,281,666 | &0000000000000745.000000745 sq mi
(&0000000000001930.0000001,930 km2) |  |
| Armstrong County | 005 | Kittanning | 1800 | Parts of Allegheny, Lycoming, and Westmoreland Counties. | John Armstrong | &0000000000072392.00000072,392 | &0000000000000664.000000664 sq mi
(&0000000000001720.0000001,720 km2) |  |
| Beaver County | 007 | Beaver | 1800 | Parts of Allegheny and Washington Counties. | Beaver River | &0000000000181412.000000181,412 | &0000000000000444.000000444 sq mi
(&0000000000001150.0000001,150 km2) |  |
| Bedford County | 009 | Bedford | 1771 | Parts of Cumberland County. | Fort Bedford, which is named for the Duke of Bedford | &0000000000049984.00000049,984 | &0000000000001015.0000001,015 sq mi
(&0000000000002629.0000002,629 km2) |  |
| Berks County | 011 | Reading | 1752 | Parts of Chester, Lancaster and Philadelphia Counties. | The English county of Berkshire | &0000000000373638.000000373,638 | &0000000000000866.000000866 sq mi
(&0000000000002243.0000002,243 km2) |  |
| Blair County | 013 | Hollidaysburg | 1846 | Parts of Huntingdon and Bedford Counties. | John Blair | &0000000000129144.000000129,144 | &0000000000000527.000000527 sq mi
(&0000000000001365.0000001,365 km2) |  |
| Bradford County | 015 | Towanda | 1810 | Parts of Luzerne and Lycoming Counties; originally called Ontario County, renamed as Bradford County in 1812. | William Bradford | &0000000000062761.00000062,761 | &0000000000001161.0000001,161 sq mi
(&0000000000003007.0000003,007 km2) |  |
| Bucks County | 017 | Doylestown | 1682 | One of the original counties at the formation of Pennsylvania | The English county of Buckinghamshire | &0000000000597635.000000597,635 | &0000000000000622.000000622 sq mi
(&0000000000001611.0000001,611 km2) |  |
| Butler County | 019 | Butler | 1800 | Parts of Allegheny County. | General Richard Butler | &0000000000174083.000000174,083 | &0000000000000795.000000795 sq mi
(&0000000000002059.0000002,059 km2) |  |
| Cambria County | 021 | Ebensburg | 1804 | Parts of Somerset and Huntingdon Counties. | Wales | &0000000000152593.000000152,593 | &0000000000000693.000000693 sq mi
(&0000000000001795.0000001,795 km2) |  |
| Cameron County | 023 | Emporium | 1860 | Parts of Clinton, Elk, McKean, and Potter Counties. | Simon Cameron | &0000000000005974.0000005,974 | &0000000000000399.000000399 sq mi
(&0000000000001033.0000001,033 km2) |  |
| Carbon County | 025 | Jim Thorpe | 1843 | Parts of Monroe and Northampton Counties. | Coal | &0000000000058802.00000058,802 | &0000000000000387.000000387 sq mi
(&0000000000001002.0000001,002 km2) |  |
| Centre County | 027 | Bellefonte | 1800 | Parts of Lycoming, Mifflin, Northumberland, and Huntingdon Counties. | Centre Furnance, owned by Samuel Miles and John Patton | &0000000000135758.000000135,758 | &0000000000001112.0000001,112 sq mi
(&0000000000002880.0000002,880 km2) |  |
| Chester County | 029 | West Chester | 1682 | One of the original counties at the formation of Pennsylvania. | The English city of Chester in the county of Cheshire | &0000000000433501.000000433,501 | &0000000000000760.000000760 sq mi
(&0000000000001968.0000001,968 km2) |  |
| Clarion County | 031 | Clarion | 1839 | Parts of Venango and Armstrong Counties. | Clarion River | &0000000000041765.00000041,765 | &0000000000000609.000000609 sq mi
(&0000000000001577.0000001,577 km2) |  |
| Clearfield County | 033 | Clearfield | 1804 | Parts of Lycoming and Huntingdon Counties; Clearfield functioned as a part of Centre County for judiciary purposes until 1822. | The cleared fields from logging in the area | &0000000000083382.00000083,382 | &0000000000001154.0000001,154 sq mi
(&0000000000002989.0000002,989 km2) |  |
| Clinton County | 035 | Lock Haven | 1839 | Parts of Lycoming and Centre Counties. | DeWitt Clinton | &0000000000037914.00000037,914 | &0000000000000898.000000898 sq mi
(&0000000000002326.0000002,326 km2) |  |
| Columbia County | 037 | Bloomsburg | 1813 | Parts of Northumberland and Luzerne Counties. | Columbia, the first popular and poetic name for the United States | &0000000000064151.00000064,151 | &0000000000000490.000000490 sq mi
(&0000000000001269.0000001,269 km2) |  |
| Crawford County | 039 | Meadville | 1800 | Parts of Allegheny County. | William Crawford | &0000000000090366.00000090,366 | &0000000000001038.0000001,038 sq mi
(&0000000000002688.0000002,688 km2) |  |
| Cumberland County | 041 | Carlisle | 1750 | Parts of Lancaster County. | The historic English county of Cumberland | &0000000000213674.000000213,674 | &0000000000000551.000000551 sq mi
(&0000000000001427.0000001,427 km2) |  |
| Dauphin County | 043 | Harrisburg | 1785 | Parts of Lancaster County. | The Dauphin | &0000000000251798.000000251,798 | &0000000000000558.000000558 sq mi
(&0000000000001445.0000001,445 km2) |  |
| Delaware County | 045 | Media | 1789 | Parts of Chester County. | Delaware River | &0000000000550864.000000550,864 | &0000000000000191.000000191 sq mi
(&0000000000000495.000000495 km2) |  |
| Elk County | 047 | Ridgway | 1843 | Parts of Jefferson, McKean, and Clearfield Counties. | Elk | &0000000000035112.00000035,112 | &0000000000000832.000000832 sq mi
(&0000000000002155.0000002,155 km2) |  |
| Erie County | 049 | Erie | 1800 | Parts of Allegheny County; attached to Crawford County until 1803. | Lake Erie | &0000000000280843.000000280,843 | &0000000000000802.000000802 sq mi
(&0000000000002077.0000002,077 km2) |  |
| Fayette County | 051 | Uniontown | 1783 | Parts of Westmoreland County. | The Marquis de Lafayette | &0000000000148644.000000148,644 | &0000000000000798.000000798 sq mi
(&0000000000002067.0000002,067 km2) |  |
| Forest County | 053 | Tionesta | 1848 | Parts of Jefferson County; attached to Jefferson County until 1857. | Chief natural feature | &0000000000004946.0000004,946 | &0000000000000431.000000431 sq mi
(&0000000000001116.0000001,116 km2) |  |
| Franklin County | 055 | Chambersburg | 1784 | Parts of Cumberland County. | Benjamin Franklin | &0000000000129313.000000129,313 | &0000000000000771.000000771 sq mi
(&0000000000001997.0000001,997 km2) |  |
| Fulton County | 057 | McConnellsburg | 1850 | Parts of Bedford County. | Robert Fulton | &0000000000014261.00000014,261 | &0000000000000438.000000438 sq mi
(&0000000000001134.0000001,134 km2) |  |
| Greene County | 059 | Waynesburg | 1796 | Parts of Washington County. | General Nathanael Greene | &0000000000040672.00000040,672 | &0000000000000578.000000578 sq mi
(&0000000000001497.0000001,497 km2) |  |
| Huntingdon County | 061 | Huntingdon | 1787 | Parts of Bedford County. | Possibly the historic English county of Huntingdonshire | &0000000000045586.00000045,586 | &0000000000000889.000000889 sq mi
(&0000000000002302.0000002,302 km2) |  |
| Indiana County | 063 | Indiana | 1803 | Parts of Lycoming and Westmoreland Counties; it was attached to Westmoreland County until 1806. | Native Americans | &0000000000089605.00000089,605 | &0000000000000834.000000834 sq mi
(&0000000000002160.0000002,160 km2) |  |
| Jefferson County | 065 | Brookville | 1804 | Parts of Lycoming County. Attached to Westmoreland County until 1806 and to Indiana County until 1830. | Thomas Jefferson | &0000000000045932.00000045,932 | &0000000000000657.000000657 sq mi
(&0000000000001702.0000001,702 km2) |  |
| Juniata County | 067 | Mifflintown | 1831 | Parts of Mifflin County. | Juniata River | &0000000000022821.00000022,821 | &0000000000000394.000000394 sq mi
(&0000000000001020.0000001,020 km2) |  |
| Lackawanna County | 069 | Scranton | 1878 | Parts of Luzerne County. | Lackawanna River | &0000000000213295.000000213,295 | &0000000000000465.000000465 sq mi
(&0000000000001204.0000001,204 km2) |  |
| Lancaster County | 071 | Lancaster | 1729 | Parts of Chester County. | The English city of Lancaster | &0000000000470658.000000470,658 | &0000000000000984.000000984 sq mi
(&0000000000002549.0000002,549 km2) |  |
| Lawrence County | 073 | New Castle | 1849 | Parts of Beaver and Mercer Counties. | The USS Lawrence | &0000000000213295.000000213,295 | &0000000000000363.000000363 sq mi
(&0000000000000940.000000940 km2) |  |
| Lebanon County | 075 | Lebanon | 1813 | Parts of Dauphin and Lancaster Counties. | Lebanon Township; Lebanon is a Biblical term meaning White Mountain | &0000000000120327.000000120,327 | &0000000000000363.000000363 sq mi
(&0000000000000940.000000940 km2) |  |
| Lehigh County | 077 | Allentown | 1812 | Parts of Northampton County. | Lehigh River | &0000000000312090.000000312,090 | &0000000000000349.000000349 sq mi
(&0000000000000904.000000904 km2) |  |
| Luzerne County | 079 | Wilkes-Barre | 1786 | Parts of Northumberland County. | The Chevalier de Luzerne | &0000000000319250.000000319,250 | &0000000000000907.000000907 sq mi
(&0000000000002349.0000002,349 km2) |  |
| Lycoming County | 081 | Williamsport | 1795 | Parts of Northumberland County. | Lycoming Creek | &0000000000120044.000000120,044 | &0000000000001244.0000001,244 sq mi
(&0000000000003222.0000003,222 km2) |  |
| McKean County | 083 | Smethport | 1804 | Parts of Lycoming County; Attached to Centre County until 1814 and to Lycoming County until 1826 for judicial and elective purposes. McKean was fully organized only in 1826. | Thomas McKean | &0000000000045936.00000045,936 | &0000000000000984.000000984 sq mi
(&0000000000002549.0000002,549 km2) |  |
| Mercer County | 085 | Mercer | 1800 | Parts of Allegheny County. | Hugh Mercer | &0000000000120293.000000120,293 | &0000000000000683.000000683 sq mi
(&0000000000001769.0000001,769 km2) |  |
| Mifflin County | 087 | Lewistown | 1789 | Parts of Cumberland and Northumberland Counties. | Thomas Mifflin | &0000000000046486.00000046,486 | &0000000000000415.000000415 sq mi
(&0000000000001075.0000001,075 km2) |  |
| Monroe County | 089 | Stroudsburg | 1836 | Parts of Pike and Northampton Counties. | James Monroe | &0000000000138687.000000138,687 | &0000000000000617.000000617 sq mi
(&0000000000001598.0000001,598 km2) |  |
| Montgomery County | 091 | Norristown | 1784 | Parts of Philadelphia County. | Uncertain; possibly either Richard Montgomery or the historic Welsh county of Montgomeryshire | &0000000000750097.000000750,097 | &0000000000000487.000000487 sq mi
(&0000000000001261.0000001,261 km2) |  |
| Montour County | 093 | Danville | 1850 | Parts of Columbia County. | Madame Montour | &0000000000018236.00000018,236 | &0000000000000132.000000132 sq mi
(&0000000000000342.000000342 km2) |  |
| Northampton County | 095 | Easton | 1752 | Parts of Bucks County. | The English city of Northampton | &0000000000267066.000000267,066 | &0000000000000377.000000377 sq mi
(&0000000000000976.000000976 km2) |  |
| Northumberland County | 097 | Sunbury | 1772 | Parts of Lancaster, Berks, Bedford, Cumberland, and Northampton Counties. | The English county of Northumberland | &0000000000094556.00000094,556 | &0000000000000477.000000477 sq mi
(&0000000000001235.0000001,235 km2) |  |
| Perry County | 099 | New Bloomfield | 1820 | Parts of Cumberland County. | Oliver Hazard Perry | &0000000000043602.00000043,602 | &0000000000000556.000000556 sq mi
(&0000000000001440.0000001,440 km2) |  |
| Philadelphia County | 101 | Philadelphia | 1682 | One of the original counties at the formation of Pennsylvania. The city and county of Philadelphia were combined in 1854 and city and county offices merged in 1952. | "Brotherly love" from Greek philos ("love") and adelphos ("brother") | &0000000001517550.0000001,517,550 | &0000000000000143.000000143 sq mi
(&0000000000000370.000000370 km2) |  |
| Pike County | 103 | Milford | 1814 | Parts of Wayne County. | Zebulon Pike | &0000000000046302.00000046,302 | &0000000000000567.000000567 sq mi
(&0000000000001469.0000001,469 km2) |  |
| Potter County | 105 | Coudersport | 1804 | From Lycoming county. Attached to Lycoming County until 1826 and to McKean County until 1835 for judicial purposes, Potter was not fully organized until 1835. | James Potter | &0000000000018080.00000018,080 | &0000000000001081.0000001,081 sq mi
(&0000000000002800.0000002,800 km2) |  |
| Schuylkill County | 107 | Pottsville | 1811 | Parts of Berks and Northampton Counties. | Schuylkill River | &0000000000150336.000000150,336 | &0000000000000778.000000778 sq mi
(&0000000000002015.0000002,015 km2) |  |
| Snyder County | 109 | Middleburg | 1855 | Parts of Union County. | Simon Snyder | &0000000000037546.00000037,546 | &0000000000000332.000000332 sq mi
(&0000000000000860.000000860 km2) |  |
| Somerset County | 111 | Somerset | 1795 | Parts of Bedford County. | The English county of Somerset | &0000000000080023.00000080,023 | &0000000000001081.0000001,081 sq mi
(&0000000000002800.0000002,800 km2) |  |
| Sullivan County | 113 | Laporte | 1847 | Parts of Lycoming County; attached to Lycoming until 1848. | John Sullivan | &0000000000006556.0000006,556 | &0000000000000452.000000452 sq mi
(&0000000000001171.0000001,171 km2) |  |
| Susquehanna County | 115 | Montrose | 1810 | Parts of Luzerne County ; attached to Luzerne County until 1812. | Susquehanna River | &0000000000042238.00000042,238 | &0000000000000832.000000832 sq mi
(&0000000000002155.0000002,155 km2) |  |
| Tioga County | 117 | Wellsboro | 1804 | Parts of Lycoming County; attached to Lycoming until 1812. | Tioga River | &0000000000041373.00000041,373 | &0000000000001137.0000001,137 sq mi
(&0000000000002945.0000002,945 km2) |  |
| Union County | 119 | Lewisburg | 1813 | Parts of Northumberland County. | The Federal union of the United States | &0000000000041624.00000041,624 | &0000000000000317.000000317 sq mi
(&0000000000000821.000000821 km2) |  |
| Venango County | 121 | Franklin | 1800 | Parts of Allegheny and Lycoming Counties; attached to until 1805. | A corruption of the Native word "onenge", meaning "otter" | &0000000000057565.00000057,565 | &0000000000000683.000000683 sq mi
(&0000000000001769.0000001,769 km2) |  |
| Warren County | 123 | Warren | 1800 | Parts of Allegheny and Lycoming counties; attached to Crawford County until 1805 and then to Venango until Warren was formally organized in 1819. | General Joseph Warren | &0000000000043863.00000043,863 | &0000000000000898.000000898 sq mi
(&0000000000002326.0000002,326 km2) |  |
| Washington County | 125 | Washington | 1781 | Parts of Westmoreland County. | George Washington | &0000000000202897.000000202,897 | &0000000000000861.000000861 sq mi
(&0000000000002230.0000002,230 km2) |  |
| Wayne County | 127 | Honesdale | 1798 | Parts of Northampton County. | Anthony Wayne | &0000000000047722.00000047,722 | &0000000000000751.000000751 sq mi
(&0000000000001945.0000001,945 km2) |  |
| Westmoreland County | 129 | Greensburg | 1773 | Parts of Bedford County. | Possibly the historic English county of Westmorland | &0000000000369993.000000369,993 | &0000000000001036.0000001,036 sq mi
(&0000000000002683.0000002,683 km2) |  |
| Wyoming County | 131 | Tunkhannock | 1842 | Parts of Luzerne County. | The Delaware word xwé:wamənk, meaning "at the big river flat" | &0000000000028080.00000028,080 | &0000000000000405.000000405 sq mi
(&0000000000001049.0000001,049 km2) |  |
| York County | 133 | York | 1749 | Parts of Lancaster County. | The English city of York | &0000000000381751.000000381,751 | &0000000000000910.000000910 sq mi
(&0000000000002357.0000002,357 km2) |  |
