In New England, anyway, while the general assumption is that everyone believes in god to some extent (and, usually, it's the Catholic version, especially as you get closer to Boston), most people are pretty private about their beliefs. So, being an atheist isn't really something that comes up. We're more united by our shared fandom with the Red Sox and Patriots than religion.
"I was thirsty for everything, but blood wasn't my style" - Live, "Voodoo Lady"