Counties formed since 1820

Blair - formed 1846 from part of Huntingdon and Bedford

Cameron - formed 1860 from part of Clinton, Elk, McKean and Potter

Carbon - formed 1843 from part of Northampton and Monroe

Clarion - formed 1839 from part of Venango and Armstrong

Clinton - formed 1839 from part of Lycoming and Centre

Elk - formed 1843 from part of Jefferson, Clearfield and McKean

Forest - formed 1848 from part of Jefferson and Venango (part of Venango was added in 1866)

Fulton - formed 1850 from part of Bedford

Juniata - formed 1831 from part of Mifflin

Lackawanna - formed 1878 from part of Luzerne

Lawrence - formed 1849 from part of Beaver and Mercer

Monroe - formed 1836 from part of Northampton and Pike

Montour - formed 1850 from part of Columbia

Snyder - formed 1855 from part of Union

Sullivan - formed 1847 from part of Lycoming

Wyoming - formed 1842 from part of Luzerne