This was rather interesting, and Rebecca, who likes maps, might like it: a geography of religious distribution in the U.S. (HT: Benj Hellie at Leiter Reports) Things that strike me on first impression as probably significant for the flow of thought in the U.S.:
(1) Catholics, while big in numbers, are spread out rather than concentrated in any one region, and appear largely on the edges of the continental U.S.
(2) Baptists, another big group, are heavily concentrated in a fairly well-defined region. So are Mormons, Methodists (to a much lesser extent), and Lutherans.
(3) Pentecostals are very evenly spread across the country, and so are, to a lesser extent, Presbyterians.
(4) On the leading religious bodies map, four groups are particularly notable as dominating regions: Baptist, Catholic, Mormon, and Lutheran.
