According to Hannah Swart in her book Koshkonong Country – A History of Jefferson County, Wisconsin, Jefferson Township was first settled by Rodney J. Currier and Andrew Lansing in December 1836 when they built a cabin in the northwest quarter of Section 10. By October 1837 a building that housed a tavern, trading post, and courthouse was built at the present site of the Jefferson County Courthouse.
The earliest record for the Town of Jefferson is a Town meeting held on April 5, 1845 when the population was listed as 75 inhabitants. The topics of discussion were raising funds to support schools, raising $100 to build bridges across the Rock and Crawfish Rivers, and appropriating $50 for a free ferry at the fork of the Rock River.
What is now the City of Jefferson operated under Town government until 1857, when the City of Jefferson was incorporated. The first settlers in the area of Helenville were John Walther, Christian Horn, Bernhard Keller, and “Old Man” Haag. The first general store was opened by Christian Lory in 1849. Helenville was named in honor of the wife of Orgies Bullwinkel who was the first postmaster. The post office was established on February 25, 1851.