1850
The town of Harmony was organized as a separate town.
Nation and worldGrade A · 1 independent source
The evidence
“The only church building over erected in this town, as well as the society, was mainly built up through the agency and .influence of Ansel Dickinson, who did more for the intellectual and religious cultivation of the children of the town than any other man during his life, His death was a serious loss, The church building has been converted into a school house, and the members are scattered abroad. The fact that the town of Harmony is so near Janesville, (forming, indeed, a part of the city,) will explain the absence of any villages or churches, , Harmony was organized as a separate town in 1850. The following is a list of tho first officers elected :”
1856-history-of-rock-county/09-harmony.md, PDF p. 100 / book p. 82
Guernsey, Orrin, and Josiah F. Willard, editors. History of Rock County, and Transactions of the Rock County Agricultural Society and Mechanics' Institute. Janesville, Wis.: William M. Doty & Brother, 1856. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871593.
Grade A: Found on a page of one of our sources