During the last half of the 20th century, most of Michigan's cities experienced a decline in population as many residents moved into developing suburbs. Particularly problematic was the phenomenon of "white flight" whereby more affluent residents who were mainly ethnically white left the cities but certain economically disadvantaged groups remained within the cities. Those who left the cities also took their tax base with them and the governments of these cities were left with having to maintain and support an older infrastructure, housing stock, and economically needy population.