I concede that segregation can allay social tensions immediately, but it further debilitates us in the long run.

When well-qualified, upper middle-class blacks or Latinos or Asians move to predominantly white neighborhoods, there's what's called the tipping point. That tipping point is generally 15 percent; at 15 percent you begin to see white flight.

I hope we have American-topias.

There is tremendous long-term harm when Americans accept ethnic and class balkanization as a de facto fixture of American life. I think that impoverishes our understanding of each other.

I concede that segregation can allay social tensions immediately, but it further debilitates us in the long run.

In the pioneer West Whitopias, immigration tended to be the dominant social and racial issue. In Forsyth County, Georgia, immigration is still an issue, but because you have that complicated history of the Trail of Tears and slavery and Jim Crow, the Whitopia has a different flavor.

Louisville, Colorado, which was just voted by CNN and Money magazine as the best place to live, is a veritable Whitopia that is unaffected by the housing crisis and even the severe recession. You look at the best places to live, according to Money's 2009 list, and 9 of the 10 are Whitopias.