Some of them just remember the 'old good days' when minorities stayed in their neighbourhoods and weren't welcomed to go out of there. The problems which were there were the minorities' problems and no one cared about them.
But at some point, when internal limits expired, these problems became problems for all. Many people, without proper skills and education, discriminated for years, became the part of American society from which they had virtually been excluded for years. And of course that couldn't go smooth. Because many just didn't find themselves in this society and engaged in a criminal way of life. That in turn resulted in more prejudice against them from the part of some people. Either this vicious circle will be broken or the US awaits really grim future.