Many Catholic parishes have kept records going back a couple hundred years. From those, you can obtain all sorts of information--deaths, marriages, baptisms, and the like. Some have financial records that can be used to gain insight into the economics of that parish and its parishioners. Tracking which priest or priests were assigned to the parish would give you an idea of what religious order might have influence over the area. If there's an archive of parish bulletins then you have a tiny newspaper--and we historians love newspapers.

Is that the kind of thing you are asking about?