An act of congress formed the Fond du Lac land district.

The evidence

• “By act of congress, approved February 24, 1855, an additional district was formed of all that portion cf the Willow river land district lying north of the line dividing townships forty and forty-one, to be called the Fond du Lac district — the office to be located by the president as he might from time to time direct. The present counties of Douglas, Bayfield, Ashland, and part of Burnett were included within its boundaries.”

  1879-history-of-rock-county/04-wisconsin-railroads-commerce-health-statistics.md, PDF p. 220

  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