Manufacturing is more efficient in single level factories as opposed to multi-level factories. The growth of efficient truck transportation means factories can relocate to rural areas where as in the past they were required out of necessity to locate in central cities along major water and rail networks. The work habits of inner city employees have been criticized. Some manufacturing concerns move to avoid unionization. Retail and wholesale trade moves to the suburbs to be where the buyers are.
People can either commute long distance or they can move .
The lack of low-income housing in suburban areas and segregated housing patterns limit the latter. Some jobs are lost to international competition Some multinational corporations move to Third World locations Jobs are eliminated through automation. Farley offers a measure of segregation called the index of dissimilarity . It's based on census tracts and describes what percentage of a city's black or white population would have to move to another census tract in order for there to be no segregation. It notes that Chicago, Cleveland, and Detroit have high levels of segregation.