What do you mean, changing demographics...the Jew thing, like before?
There is pretty much an accepted criteria for what is a "good" neighborhood and what is a bad neighborhood. As time drifts on, the original inhabitants of a neighborhood leave it, newcomers replace it. In some cases, such as the neighborhoods which we now are looking in for houses, the newcomers kept the neighborhood as the old residents did. These neighborhoods in time become "historical districts", "retro", the kind of inner-city communities where home prices shoot up because they stay safe, clean and a wonderful place to raise children, and often they become expensive because they are an island surrounded by the other type, and this is the kind I live near
These are the older working class neighborhoods who as time goes by, residents die, move out, new ones replace them. These neighborhoods often have a period of rapid sell off at rock bottom prices, leading to the wide belief among many who would otherwise buy there that this is a bad area. May not be true at the time, but this becomes a self-fulfilling prophecy. Soon, the neighborhood looks more ragged, apparently the newcomers have no interest in keeping up their homes, as time goes on, the last of the old resident moves out and soon, you have a ghetto on your hands, a place where drugs are rampant, the schools are bad, many homes have overgrown yards, burglar bars, etc, and where, if you look at the booking record at a county jail, many of their arrestees seem to claim homes in said area as their residence.
Most of the city outside of of the 56 limits was built between 1940-1970, these neighborhoods have all exited (or about to) exit their first generation, and the city has annexed no new territory. It's in the city's interest to keep as many nice areas as possible while curtailing the spread of bad areas as much as possible.