Preaching styles and people being slain in the spirit and things like that. Now it doesn't happen in all black churches, and it happens sometimes in white churches, right? But on average they're quite a bit different.

So we didn't get the denominations and the separate congregations really till about into Civil War time. What's happened then, of course, is now that we've had well over 100 years of this history to establish separate cultures, different ways of worshipping, and different ways of understanding theology so that when people try to come together makes it very difficult. And then, of course, social networks, you know, how do we find a place to worship?

And different traditions stress different - so then there's that. I talked to an African American who says before she goes into an interracial church, she sits in her car and she listens to gospel music to get her fill, and she goes into an interracial church where they don't do gospel music, and she's ready to accept the other sorts of ways of worshipping. So there's that.

I mean, so if I've talked to whites in City of Refuge, sometimes they'll wonder, "Why do we do things a certain way, and why do we make a big deal out of events?" And what's happening is they're falling back on their understanding of the way that church should work. It's not always working exactly like that, and they feel frustration or confusion. Sometimes people leave. That's certainly common in mixed churches.

So it may be a language that separates you - again, social networks. But second-generation Asian and Hispanics, second, and third and fourth and so on, they are much more likely to be in integrated churches than are blacks or whites.

Now they had to sit in separate places and sometimes they'd even have to sit outside and look through the windows. But they did worship together.

It happens a little bit more in the West, where there's more fluid - where everybody's originally from somewhere else. So they have a little bit more permission to do it. It happens the least, at the individual level at least, in the South, because the South has very strong, you know, set up black churches and white churches and a long history of that, and so it's a bigger social cost.