Townships 1, 2, 3 and 4 north of Range 10 east (later Avon, Spring Valley, Magnolia and Union) were added to Rock County.

The evidence

• “By an act, approved June 21, 1838, Townships 1, 2, 8 and 4 north, of Range 10 east, subsequently the towns of Avon, Spring Valley, Magnolia and Union, were added to Rock County, thus giving it the boundaries and configuration it has since retained. Though thus enlarged, the new county remained attached to Racine County for judicial purposes, until its organization ; meanwhile by an act, approved December 27, 1837, the seat of justice was located on " part of the northwest quarter of Section 36, in Town 3 north, of Range 12 east, of the Fourth Principal Meridian."”

  1879-history-of-rock-county/09-rock-county-ch03-pioneer-reminiscences.md, PDF p. 353 / book p. 357

  Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.

  Grade A: Found on a page of one of our sources