Wis. Stat. § 229.823
A district's jurisdiction is any county with a population at the date of the district's creation of more than 150,000 that includes the principal site of a stadium that is home to a professional football team, that is a member of a league of professional football teams that have home stadiums in at least 10 states and a collective average attendance for all league members of at least 40,000 persons per game over the 5 years immediately preceding the year in which a district is created, and that is approved by that league for use as a home stadium for that professional football team. Once created, the district's jurisdiction remains fixed even if population or attendance figures subsequently decline below the minimums described in this section.
Wis. Stat. § 229.823