Wisconsin County Creation Dates and Parent Counties

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The following is a list of the counties that have existed in Wisconsin from the time it gained territorial status (20 April 1836) up to the present. It excludes those counties that were created in the area that became Iowa Territory on 4 July 1838.

Before becoming a territory the area that now makes up Wisconsin belonged to the following jurisdictions:

Northwest Territory - 13 July 1787 to 7 May 1800

Indiana Territory - 7 May 1800 to 1 March 1809

Illinois Territory - 1 March 1809 to 18 April 1818

Michigan Territory - 18 April 1818 to 20 April 1836

For a detailed look at the formation of Wisconsin Counties between 1818 and 1909 see:

Kellogg, Louise Phelps. "Organization, Boundaries, and Names of Wisconsin Counties," in Proceedings of the States Historical Society of Wisconsin. 57 (1909), 184-231.

Maps of the boundary changes of Wisconsin counties are hosted at FamilyHistory101.com.