The opposite of "gentrification." Disinvestment and the creation of deteriorated property caused by lower-income people slowly taking over and moving in to middle-class neighborhoods resulting in the flight of the former wealthier inhabitants.
In Detroit, a large proportion of ghettofied housing was originally built for middle and upper income occupants. As the process of ghettofication occurred this housing was increasingly occupied by lower income people. The ensuing disinvestment caused a spiral of decline in this former neighborhood of gentry as mansions were subdivided into several apartments with impoverished tenants. As ghettofication increased the houses were not maintained and blight engulfed the neighborhood.