Wayne County is the most populous county in the U.S. state of Michigan. As of the 2010 census, its population was 1,820,584, making it the 17th-most populous county in the United States. The county seat is Detroit, the most populous city in Michigan and 18th-most populous city in the United States. The county was founded in 1796 and organized in 1815.
Wayne County was the sixth county in the Northwest Territory, formed 15 August 1796 from portions of territorial Hamilton County, territorial Knox County and unorganized territory. It was named for the American general "Mad Anthony" Wayne. It originally encompassed the entire area of the Lower Peninsula of Michigan, as well as smaller sections that are now part of northern Ohio, Indiana and Illinois. By proclamation of the Territorial Secretary and Acting Governor, Winthrop Sargent, on August 15, 1796, the boundaries of Wayne County were declared to begin at the mouth of the Cuyahoga River then west to Fort Wayne, then to the southernmost point of Lake Michigan and along the western shore north to the territorial boundary in Lake Superior and then along the territorial boundary through Lake Huron, Lake St. Clair, and Lake Erie back to the starting point.
On January 14, 1803, the Governor of Indiana Territory, William Henry Harrison, issued a similar proclamation defining the boundaries as beginning at a point where an east and west line passing through the southernmost extreme of Lake Michigan would intersect a north and south line, passing through the westernmost extreme of the lake, then north to the territorial boundary, then along said boundary line to a point where an east and west line passing through the southerly extreme of Lake Michigan would intersect the same, then along this last mentioned line to the place of beginning. This boundary would include Chicago, Illinois and a sizable strip of Wisconsin along Lake Michigan.
Note: Total for 1800 comprises population reported for Wayne County, Northwest Territory (which may have included some persons in present-day northern Ohio), and for Machilamackanack, Indiana Territory (251 persons and 300 "boatmen from Canada, &c."). Total for 1820 excludes population (1,444) of Brown and Crawford Counties, and total for 1830 excludes population (3,635) of Brown, Crawford, and Iowa Counties, all enumerated in what is now Wisconsin. Total for 1890 includes 1 Indian in prison, not reported by county.. The 1810 census was reported in terms of four Civil Districts of a single Wayne County: Michilimackinac, Detroit, Erie, and Huron. The 1810 population shown in the table for Mackinac County is that reported for Michilimackinac Civil District, for Macomb County that reported for Huron Civil District, for Monroe County that reported for Erie Civil District, and for Wayne County that reported for Detroit Civil District.