Racial segregation in housing is a persistent and pernicious problem in American life.\u00a0If neighborhoods are filled predominantly by one race or another, that group of people can be advantaged or disadvantaged by virtue of where they live.\u00a0Decisions about where to put parks, garbage dumps, toxic facilities, airports, and highways, for example, can affect some groups more than others. Some neighborhoods might not have good\u00a0jobs or public transportation, or sufficient numbers of grocery stores, nursing homes, or recreation facilities, but be filled with check cashing businesses, liquor stores, and cigarette advertising.\u00a0The quality of schools, water systems, levee systems, and even the air itself varies by neighborhood.\u00a0And a large and robust literature in sociology shows that good things tend to cluster in whiter neighborhoods and bad things in neighborhoods that are predominantly African American or Latino.<\/p>\n
But why are neighborhoods racially segregated?\u00a0And why do they resist integration?<\/p>\n
One possibility is that white people\u00a0simply prefer to live among others of the same race. What comes to mind perhaps is a white family that sells their house the second a black family moves in next door, but a model developed by economist Thomas Schelling\u00a0shows that even a surprisingly weak\u00a0preference\u00a0will produce systemic segregation.<\/p>\n
What if, for example, there are two types of people and each are happy in a diverse neighborhood, but\u00a0they become uncomfortable when fewer than 1\/3rd of their neighbors are like them? If you randomly move the uncomfortable households around until everyone’s happy, segregation is mathematically guaranteed. Here is a simulation, at the Parable of the Polygons<\/a>\u00a0(h\/t orgtheory<\/a>), of how segregation results from a preference that 1\/3rd or more of one’s neighbors are the same race:<\/p>\n