This is a list of U.S. counties that were established by a state, provincial, colonial, or territorial government, which no longer exist, for one reason or another. This does not include counties that were renamed but retained their territorial integrity, or counties that were transferred wholesale to another state when it was separated from another state (Massachusetts counties transferred to Maine; Virginia counties transferred to West Virginia).
Pautah County, California - created by the California legislature out of territory the state believed would be ceded to it north of Lake Tahoe, but which was given to Nevada. County never officially organized.
Crocker County, Iowa Iowa's 100th, "Lost County". Created in 1870 from portions of Bancroft County. The county seat was located at Greenwood, Iowa. In December, 1871, the Supreme Court of Iowa declared the act creating this county a violation of the constitution, which in article eleven declares that no new county shall be created which contains less than four hundred thirty two square miles. As Crocker County was smaller than the law allowed for, it ceased to exist from and after the rendition of that decision and its territory reverted to Kossuth County. To this day, Iowa is divided into just 99 counties.
Pembina County, Minnesota Territory (1849-1858, reconstituted as Pembina County, Dakota Territory in 1861, eventually reduced to present-day Pembina County, North Dakota.)
Yorkshire County, Province of New York (original English county, partitioned in 1683 into Kings, Queens (including modern Nassau), Suffolk, Richmond and Westchester (including modern Bronx) counties.)
Washington County, Republic of Vermont (1781-1782, land now in New Hampshire; Vermont relinquished claim; there is a present-day "new" Washington County, Vermont)
