Wisconsin holds a judicial primary election on February 18, 2020. A State Supreme Court seat is on that ballot. On December 13, an Ozaukee County Circuit Judge ordered the State Board of Elections to remove 234,000 registered voters, all of whom either did not respond to an October 2019 mailing asking them to re-affirm their residence, or for whom the post office could not deliver the notice. See this story. Wisconsin has election-day registration.