Part of the problem is the color coding program started in 1937 by the US gov that went to somewhere mid 60's. It created MASSIVE disinvestment in cities and concentrated poverty. Between that, the highway system and cars available to such a large percentage of the US population, the US policies that favored new builds over fixing up existing housing, and the way we pay for schools that creates horrible ones in inner cities (areas of the most disinvestment over the last many decades) that bars people with children who have options and would WANT to live in urban areas from doing so...we've spent a long time taking many US cities apart. With predictable results.