This chapter explores the theoretical economic foundations of two main drivers of shrinkage and decline: suburbanization and deindustrialization. Maintaining the city-suburb dichotomy diverts attention from important patterns of actually existing and decline, which can and do occur beyond central city borders in the United States. The chapter focuses on longitudinal census tract-level data to demonstrate these patterns and presents findings that suggest that the phenomena of shrinkage, decline, and coupled shrinkage and decline could be in the beginning stages of a longer-term shift away from central cities toward the inner suburbs. It presents a brief illustrative case study of the Greater St. Louis metropolitan region. The bid-rent model was proposed in the 1960s by William Alonso to explain patterns of metropolitan land values and the distribution of land across different classes of end users. The chapter explains a glimpse into the changing patterns of decline in a single metropolitan region.