In Missouri, there are a series of towns along and near the Missouri river between Jefferson City and St. Louis that were founded by German Catholics, and some of the counties there are still plurality Catholic. Hermann, Missouri springs immediately to mind. It was/is known for it's german vinters.
Perry and Osage Counties come to mind for me. Perry County is about 60% Catholic and is heavily Republican, as is Osage County one of the most Republican counties in the state. Osage contains the community of Westphalia where even the streets are labeled in German. Other counties in what's known as the Missouri Rhineland are strongly GOP as well; Hermann, as you've mentioned, is in Gasconade County and has one of the longest Republican streaks in the state as no Democrat has carried the county in a presidential election since before the Civil War (!). I think most of Gasconade is Dutch-German though. My home county of Bollinger contains a community called Leopold which has one of the highest concentrations of Dutch Germans in the state and is almost uniformly Catholic and heavily Republican. You can't go hardly anywhere in Leopold without seeing a pro-life yard sign or a statue of Mary in their yards. Common last names here are of German descent, including Vandeven, VanderMierden, Stoverink, Jansen, Nenninger, Seiler, Eftink, Elfrink, Thiele, Horrell, etc. In fact, there are only two Catholic churches in Bollinger County: one (St. John's) is located in Leopold (directly across from the "public" school), while the other (St. Anthony's) is in Glennon, a "suburb" of Leopold.
