The city of Ferguson has been in the news this past year because of a white cop killing a black teen. There's lots of news about how it is a predominantly black city, mostly poor, with a mostly white police force. There's lots of commentary about how the police should become more racially mixed or maybe even predominantly black. The police also need a great deal of racial sensitivity training. This solution was also recommended for other cities with racial conflicts between police and residents.
Richard Rothstein, a Research Associate at the Economic Policy Institute writing for Washington Spectator, says that isn't enough. To explain why he delves into how Ferguson got to be predominantly black.
Short answer: Intentional segregationist government policy.
In detail: A century ago St. Louis was one of several cities that prohibited integrated neighborhoods. The Supremes banned such laws in 1917. St. Louis responded by requiring white neighborhoods to have only single-family homes (which blacks had a hard time to afford) and black neighborhoods have multi-family structures, saloons, and factories. Baltimore would condemn a house if it was black owned and in a white neighborhood.
In the 1930s the federal gov't financed razing old neighborhoods and building explicitly segregated housing. During WWII housing for defense workers was also segregated. Funding of segregated housing continued in 1949 in spite of an effort towards integration.
When the federal gov't promoted suburbanization the Federal Housing Administration guaranteed bank loans to builders only if homes were not sold to blacks. The FHA provided model deeds showing how to prevent resale to blacks. It also did "redlining," refusing to insure houses in black neighborhoods and declaring them to be uncreditworthy.
Factories – jobs in general – followed whites to the suburbs. Blacks couldn't follow. They were restricted to areas where rents became high through high demand and low availability. Or they were given mortgages that never gave them equity. Many had to share housing. Overcrowded neighborhoods near city centers became targets of "slum clearance" programs. The residents were given vouchers that only certain landlords would accept. That's how blacks were moved out of St. Louis and crowded into Ferguson.
White families could use home equity to send their children to college. Black families could not. Black income is now about 60% of white income (that's bad enough), but black home equity is only 5% of white home equity.
Federal policy, with help at the state and local level, prohibited blacks from accumulating equity during the suburban boom. These policies have never been remedied. Without that remedy – policies to facilitate desegregation – incidents like Ferguson will continue.