Denton county (one of the depressingly blue ones directly north of Dallas county) is where most of the evangelicals live now...Dallas county's pretty diverse, to say the least.
I always thought of Denton county and the suburbs around Dallas as ground zero for white evangelical Christians living in their McMansions, is there anywhere else in the country that has a greater concentration, maybe suburban Atlanta?
Yes, North Fulton specifically. There is a huge mega church in Alpharetta called North Point that has at least 10,000 members. The area is very wealthy and well educated but it's remained very conservative partly because of the evangelical culture there. But it's more Colorado Springs than Bible Belt religiosity.
Houston would also count too. Joel Osteen's church is there and it's massive. And then of course you have Orange County, CA....