| County | County Seat | Date Created | Notes |
|---|---|---|---|
| Albany | Albany | 1683 | |
| Allegany | Belmont | 1806 | |
| Bronx | Bronx | 1914 | |
| Brooklyn | See Kings. | ||
| Broome | Binghamton | 1806 | |
| Cattaraugus | Little Valley | 1808 | |
| Cayuga | Auburn | 1799 | |
| Charlotte |
See Washington. Renamed in 1784. | ||
| Chautauqua | Mayville | 1808 | |
| Chemung | Elmira | 1798 | |
| Chenango | Norwich | 1798 | |
| Clinton | Plattsburgh | 1788 | |
| Columbia | Hudson | 1786 | |
| Cortland | Cortland | 1808 | |
| Delaware | Delhi | 1797 | |
| Dutchess | Poughkeepsie | 1683 | |
| Erie | Buffalo | 1821 | |
| Essex | Elizabethtown | 1799 | |
| Franklin | Malone | 1808 | |
| Fulton | Johnstown | 1838 | |
| Genesee | Batavia | 1802 | |
| Greene | Catskill | 1800 | |
| Hamilton | Lake Pleasant | 1816 | |
| Herkimer | Herkimer | 1791 | |
| Jefferson | Watertown | 1805 | |
| Kings | Brooklyn | 1683 | Brooklyn |
| Lewis | Lowville | 1805 | |
| Livingston | Geneseo | 1821 | |
| Madison | Wampsville | 1806 | |
| Manhattan |
See New York. | ||
| Monroe | Rochester | 1821 | |
| Montgomery | Fonda | 1772 | Originally Tryon; renamed Montgomery in 1784. |
| Nassau | Mineola | 1899 | |
| New York | New York | 1683 | Manhattan |
| Niagara | Lockport | 1808 | |
| Oneida | Utica | 1798 | |
| Onondaga | Syracuse | 1794 | |
| Ontario | Canandaigua | 1789 | |
| Orange | Goshen | 1683 | |
| Orleans | Albion | 1824 | |
| Oswego | Oswego | 1816 | |
| Otsego | Cooperstown | 1791 | |
| Putnam | Carmel | 1812 | |
| Queens | Jamaica | 1683 | |
| Rensselaer | Troy | 1791 | |
| Richmond | St. George | 1683 | Staten Island |
| Rockland | New City | 1798 | |
| St. Lawrence | Canton | 1802 | |
| Saratoga | Ballston Spa | 1791 | |
| Schenectady | Schenectady | 1809 | |
| Schoharie | Schoharie | 1795 | |
| Schuyler | Watkins Glen | 1854 | |
| Seneca | Waterloo | 1804 | |
| Staten Island | See Richmond. | ||
| Steuben | Bath | 1796 | |
| Suffolk | Riverhead | 1683 | |
| Sullivan | Monticello | 1809 | |
| Tioga | Owego | 1791 | |
| Tompkins | Ithaca | 1817 | |
| Tryon | See Montgomery. Renamed in 1784. | ||
| Ulster | Kingston | 1683 | |
| Warren | Lake George | 1813 | |
| Washington | Fort Edward | 1772 | Originally Charlotte; renamed Washington in 1784. |
| Wayne | Lyons | 1823 | |
| Westchester | White Plains | 1683 | |
| Wyoming | Warsaw | 1841 | |
| Yates | Penn Yan | 1823 |