Megan McCardle uses my idea

Kinda cool.

A couple of days ago Megan McCardle in The Atlantic wrote a story titled "The Gentrifier's Lament". Here's the opening:
So having finally closed on the house, we're living in what is euphemistically known as a "mixed" neighborhood, where poor black residents who have lived there for a generation or more exist somewhat uncomfortably side-by-side with more affluent whites who are drawn to the relatively cheap rents and lovely Victorian housing stock. The tensions thus built up are played out in many places, notably local politics, where a recent attempt by a local cafe to get a liquor license triggered many of the arguments that we heard after Adrian Fenty's loss in the mayoral race.

Yesterday, I rode the bus for the first time from the stop near my house, and ended up chatting with a lifelong neighborhood resident who has just moved to Arizona, and was back visiting family. We talked about the vagaries of the city bus system, and then after a pause, he said, "You know, you may have heard us talking about you people, how we don't want you here. A lot of people are saying you all are taking the city from us. Way I feel is, you don't own a city." He paused and looked around the admittedly somewhat seedy street corner. "Besides, look what we did with it. We had it for forty years, and look what we did with it!"
It goes on to discuss how neighborhoods change from white to black and back again, from poor to rich, and so forth.

It put me in mind of an old article I read back in 2002. I actually was able to remember that it was also in The Atlantic. I figured out a keyword from that old article and was able to find it again. It was "Seeing Around Corners" by Jonathon Rauch. In the article, he talked about a researcher, Thomas Schelling, who used computer modeling of neighborhoods to see how they change over time. One model Schelling built was very simple: how would a neighborhood change over time if each individual would prefer having at least two neighbors of the same race. In the end, he determined that, even if each individual wanted to live in a diverse community, their desire to have at least 2 same-race neighbors would eventually result in solid segregation:
In the random distribution, of course, many agents are unhappy; and in each of many iterations [...] unhappy agents are allowed to switch places. Very quickly ... the reds gravitate to their own neighborhood, and a few seconds later the segregation is complete: reds and blues live in two distinct districts....

...When I first looked at it, I thought I must be seeing a model of a community full of racists. I assumed, that is, that each agent wanted to live only among neighbors of its own color. I was wrong. In the simulation I've just described, each agent seeks only two neighbors of its own color. That is, these "people" would all be perfectly happy in an integrated neighborhood, half red, half blue. If they were real, they might well swear that they valued diversity. The realization that their individual preferences lead to a collective outcome indistinguishable from thoroughgoing racism might surprise them no less than it surprised me...
I then posted a comment on McCardle's piece quoting from the other Atlantic article.

Today, McCardle followed up on her article with another, "Gentrification and Its Discontents", which went deeper into the issue of the first post.

And how did she end today's post?...This way:
But the stable mixed-income neighborhood with something for anyone remains very much a goal, rather than an achievement, of city planners.

An article from our pages several years ago might explain why. Jonathan Rauch watched simulated societies in a computer, and noted what happened even when the "people" of the model had only a modest preference for being around others like them:

[ Extended quote from the Rauch article I handed her on a silver platter! ]

This is not just true of race; it is true of a number of characteristics, especially economic class. Which is understandable, because neighborhoods have network effects. Having more people like you means having more services for people like you, which is very valuable. Unfortunately, even a very mild preference for being around a few of your "own kind" seems to result in fairly homogenous neighborhoods--which explains, in this era of labor mobility, why people seem to live around others who are not only similar in income and race, but also in political views and other characteristics. A city planner trying to fight this has a heroic task in front of them.

None of this is new, of course; it's a bog standard debate in most urban centers. The problem can also be readily observed in situ by going to the many cities which have enacted inclusionary zoning and similar measures in response to gentrification, yet still seem to be gentrifying. If Ms. Baca wants me to "change my attitude" about this area of city planning, she is going to need to offer a little more than a lecture. I'm going to need some actual evidence--and so far, she's utterly failed to provide it
You're welcome, Ms. McCardle :)