Back in the early 2000s, the Fifth District appellate court in Illinois was composed of 6 Democratic judges and 1 Republican. That appellate district sits above Madison and St. Clair Counties, which were then and still are famous venues for mass tort claiming.
Today, things are very different. Now, the count is six Republican judges and 1 Democrat. There are many reasons for the changes; some of them are described in this September 3, 2019 article in the Madison-St. Clair Record.
The overall point is larger. The point is that judicial change can occur when there are concentrated efforts over time in a few key places.