County Formed County seat Named after
Albany County November 1, 1683 as one of the original 12 counties Albany the Duke of York and Albany.
Allegany County April 7, 1806 from part of Genesee County Belmont the Allegheny River.
Bronx County April 19, 1912 from part of New York County that originally was in Westchester County Coextensive with The Bronx in New York City Jonas Bronck
Broome County March 28, 1806 from part of Tioga County Binghamton John Broome.
Cattaraugus County March 11, 1808 from part of Genesee County Little Valley a Seneca phrase meaning "bad smelling banks" (referring to the odor of natural gas which leaked from local rock formations).
Cayuga County March 8, 1799 from part of Onondaga County Auburn the Cayuga tribe
Chautauqua County March 11, 1808 from part of Genesee County Mayville a Seneca word meaning "where the fish was taken out."
Chemung County March 29, 1836 from part of Tioga County Elmira a Lenape word meaning "big horn", which was the name of a local Indian village
Chenango County March 15, 1798 from parts of Tioga County and Herkimer County Norwich an Onondaga word meaning "large bull-thistle"
Clinton County 1788 from part of Washington County Plattsburgh George Clinton
Columbia County 1786 from part of Albany County Hudson Christopher Columbus
Cortland County 1808 from part of Onondaga County Cortland Pierre Van Cortlandt
Delaware County 1797 from parts of Otsego County and Ulster County Delhi Thomas West, Lord De La Warr
Dutchess County 1683 as one of the original 12 counties Poughkeepsie Lady Anne Hyde, the Duchess of York
Erie County 1821 from part of Niagara County Buffalo the Erie tribe.
Essex County 1799 from part of Clinton County Elizabethtown the county of Essex in England.
Franklin County 1808 from part of Clinton County Malone Benjamin Franklin.
Fulton County 1838 from part of Montgomery County Johnstown Robert Fulton.
Genesee County 1802 from part of Ontario County Batavia a Seneca phrase meaning "good valley".
Greene County 1800 from parts of Albany County and Ulster County Catskill Nathanael Greene.
Hamilton County 1816 from part of Montgomery County Lake Pleasant Alexander Hamilton.
Herkimer County 1791 from part of Montgomery County Herkimer Nicholas Herkimer.
Jefferson County 1805 from part of Oneida County Watertown Thomas Jefferson.
Kings County 1683 as one of the original 12 counties Coextensive with Brooklyn in New York City. King Charles II of England.
Lewis County 1805 from part of Oneida County Lowville Morgan Lewis.
Livingston County 1821 from parts of Genesee County and Ontario County Geneseo Robert R. Livingston
Madison County 1806 from part of Chenango County Wampsville James Madison
Monroe County 1821 from parts of Genesee County and Ontario County Rochester James Monroe
Montgomery County 1772 from part of Albany County Fonda. originally Tryon County. renamed after Richard Montgomery in 1784
Nassau County 1899 from Queens County Mineola William of Nassau
New York County 1683 as one of the original 12 counties Coextensive with Manhattan in New York City
Niagara County 1808 from part of Genesee County Lockport an Indian word meaning "thunder of waters"
Oneida County 1798 from part of Herkimer County Utica the Oneida tribe
Onondaga County 1792 from part of Herkimer County Syracuse the Onondaga tribe
Ontario County 1789 from part of Montgomery County Canandaigua an Iroquois word meaning "beautiful lake"
Orange County 1683 as one of the original 12 counties Goshen William of Orange
Orleans County 1824 from part of Genesee County Albion the French Royal House of Orleans.
Oswego County 1816 from parts of Otsego County and Onondaga County Pulaski.
Otsego County 1791 from part of Montgomery County Cooperstown.
Putnam County 1812 from part of Dutchess County Carmel Israel Putnam.
Queens County 1683 as one of the original 12 counties Jamaica. Coextensive with Queens in New York City
Rensselaer County 1791 from part of Albany County Troy Killiaen Van Rensselaer
Richmond County 1683 as one of the original 12 counties St. George. Coextensive with Staten Island in New York City. the title of the illegitimate son of King Charles II of England.
Rockland County 1798 from part of Orange County New City. early settlers' description of terrain as "rocky land".
Saratoga County 1791 from part of Albany County Ballston Spa.
Schenectady County 1809 from part of Albany County Schenectady Mohawk phrase meaning "on the other side of the pine lands".
Schoharie County 1795 from parts of Albany County and Otsego County Schoharie.
Schuyler County 1795 from parts of Chemung County, Steuben County, and Tompkins County Watkins Glen Philip Schuyler.
Seneca County 1804 from part of Cayuga County. County seats: Ovid and Waterloo the Seneca tribe
St. Lawrence County 1802 from parts of Clinton County, Herkimer County, and Montgomery County Canton
Steuben County 1796 from part of Ontario County Bath Friedrich von Steuben.
Suffolk County 1683 as one of the original 12 counties Riverhead
Sullivan County 1809 from part of Ulster County Monticello John Sullivan
Tioga County 1791 from part of Montgomery County Owego an Indian word meaning "at the forks," describing a meeting place
Tompkins County 1817 from parts of Cayuga County and Seneca County Ithaca Daniel D. Tompkins
Ulster County 1683 as one of the original 12 counties Kingston
Warren County 1813 from part of Washington County Lake George General Joseph Warren
Washington County 1772 from part of Albany County Hudson Falls. originally Charlotte County; renamed after George Washington in 1784
Wayne County 1823 from parts of Ontario County and Seneca County Lyons General Anthony Wayne.
Westchester County 1683 as one of the original 12 counties White Plains
Wyoming County 1841 from part of Genesee County Warsaw.
Yates County 1823 from parts of Ontario County and Steuben County Penn Yan Governor Joseph C. Yates.
