Digital cartographer Eric Fischer has compiled data from the 2000 census, and mapped 100 American cities by race. Some of the cities he did (such as New York City, Chicago, Detroit and Philadelphia) show stark lines separating different communities. Tulsa and Oklahoma City made his list of 100 cities to map.
Here's the Tulsa map (click for a larger view, or click the Tulsa link above):
Here's the Oklahoma City map (click for a larger view, or click the OKC link above):
From Fischer: "Red is White, Blue is Black, Green is Asian, Orange is Hispanic, Gray is Other, and each dot is 25 people. Data from Census 2000."