In 2018, the Wisconsin State Department of Health estimated over 3000 surveillance case reports for Lyme Disease in Wisconsin. Since many cases go unreported, this is an underestimate of the actual incidence of this illness. A recent evaluation of surveillance reports and disease incidence by CDC implies that there may actually be 20-40,000+ cases of Lyme Disease in Wisconsin each year. Visit the Wisconsin Department of Health Services for more information about surveillance and disease.
The incidence of Lyme disease is lower in the southern and eastern counties of Wisconsin. This is likely related to land cover, as the deer tick is tightly linked to forested environments. Forests and woods are less common in the lower incidence southern and eastern counties. See the USGS website for a view of forest canopy in the state https://archive.usgs.gov/archive/sites/landcover.usgs.gov/wisconsin.html
However, deer ticks are still found in these counties wherever patches of forest occur.