Defining employment centers in Milwaukee : a GIS solution to boundary questions
The purpose of this paper is to define the employment centers in metropolitan Milwaukee by using the ratio of workers working in a census tract to workers living in the tract (E/R ratio) as a primary criterion. Following the review of spatial concepts of urban structure and previous literature, the 1990 spatial patterns of population, resident workers, and employment in greater Milwaukee are mapped, summarized in tabular form, and compared. This study was conducted in a geographic information system (GIS), capable of integrating, transforming, and displaying all forms of geographically referenced data. In addition, digital raster graphics (DRGs), digital topographic images produced by the United States Geological Survey (USGS), provided a wealth of site specific information and assisted in delimiting employment center boundaries and in assigning employment center names. Overall, 30 employment centers were identified and named. While downtown Milwaukee is still the largest concentration, containing almost 12 percent of the total area jobs, the pattern of decentralization is observed as the distribution of employment occurs throughout most of the urbanized areas. As this study replicated the method Forstall and Greene developed for Los Angeles, comparisons of decentralization between Milwaukee and Los Angeles were made to examine whether or not their conclusions apply to other metropolitan areas such as Milwaukee. In the two metropolitan areas, over 60 percent of jobs were contained in the employment centers. Nevertheless, Los Angeles exhibited a higher level of job decentralization than Milwaukee, where job concentrations were located throughout most of the Los Angeles urbanized area with a small portion of jobs in its downtown. The substantially high number of jobs in downtown Milwaukee and relatively moderate number of jobs found in other job concentrations suggest a threshold, in which a metropolitan area grows and expands large enough to include several downtowns in suburbs that are functionally independent.