Missouri
Missouri’s Supreme Court has seven justices. Currently there are four Democratic justices and three Republican justices. Missouri conducts retention elections, which means that the governor appoints a justice, who then must be retained or voted out by the voters at the end of the term. In 2020, one justice is up for retention. This means that if a Justice receives a majority Yes vote in the election, s/he will serve for another term on the court before appearing on the ballot for another retention vote. If a Justice receives a majority No vote, s/he will be replaced by Republican Governor Mike Parson.
Justice Patricia Breckenridge has been on the court since 2007, when she was appointed by Republican Governor Matt Blunt.