Thanks for putting this up Mike. This kind of stuff always fascinates me, and I have visited upon Glenmary's work before, and appreciated it.
The percentage of adherents figures look bogus to me. Given for example that about 12%-13% or something of the population is black, then that 1.6% for Black Protestants means that only about 15% or so of the blacks are Protestants. Really? The Catholic percentage of 38% or so also looks way high. It might be closer to 25%. Maybe the issue is that "adherents" really means "congregants," and those who claim an affiliation, may not be members of any congregation, and far more Catholics tend to be congregants than blacks. Or something.
The first map is a little misleading if you automatically assume those not claimed by a religious group are not religious. For example a lot of Appalachia is not claimed by a religous group, whereas Los Angeles County has a very high participation rate. It's mainly due to Catholic knowing very well how many participants they have, whereas in parts of the country where there are a lot of random small churches, they might not be getting counted in this survey.
