Religion in North America.

Here are two interesting maps showing various aspects of religion in the U.S. (using 2000 Census information on a county-by-county basis). [via Matthew Yglesias and Regions of Mind]

This first map shows the dominant religious affiliation in the U.S. The red part, which corresponds to what is known as “the Bible Belt” (in the Southeast) represents the counties where the Baptist Church is predominant (see more info on the Baptist Church here). More surprisingly is the overall Catholic presence in the blue counties. (It is not just because of the hispanic immigrants - the fact that the Catholic Church is a more unified body may also have a lot to do with it):

This second map is more interesting – and stupendous, I think. It shows the degree of religious adherence according to one's acknowledged membership in a particular religious grouping. It seems it is now the Mid-Atlantic region which is become more religious. This needs to be checked by other studies but it may be the sign of the demise of the traditional “Bible Belt” and the tailoring of a “Bible Tie”:

NOTE: As you can read in this Wikipedia article on Evangelicalism, denominations in the U.S. can be very tricky and are based not just on personal faith and theology but also (and I would say primarily) on cultural identification, so the findings here above should be taken with a grain of salt.