Abstract: Geographical centers of economic activity have led to a wide range of conceptual frameworks and theories in order to explain patterns of development and interaction in cities. An active engagement of scholars across a number of fields underlies this dissertation's new method to define intra-urban centers within a spatial-economic framework, and both employment and establishment patterns are critical to a definition of 'centers.' Using a Gaussian-based kernel-smoothing process on the establishment and employment distributions, this dissertation generates the center locations and investigates their economic properties. A binary choice model assesses the factors that drive establishment location in a center, finding that larger and quaternary-service based establishments are more likely to locate within centers. A case study is developed around Phoenix, an exemplar city that has grown by more than a factor of thirty between 1950 and 2005 and is one of the largest and fastest-growing metropolitan areas in the United States. In order to show temporal change in this rapidly growing metropolitan area, centers are identified and investigated for the time periods of 1995 and 2004.