Do New Economic Geography Agglomeration Shadows Underlie Current Population Dynamics across the Urban Hierarchy

The New Economic Geography (NEG) was motivated by the desire to formally explain the emergence of the American urban system. Although the NEG has proven useful in this regard, few empirical studies investigate its success in explaining current population dynamics in a more developed mature urban system, particularly across the urban hierarchy and in the rural hinterlands. This study explores whether proximity to same-sized and higher-tiered urban centers affected the patterns of 1990-2006 U.S. county population growth. Rather than casting agglomeration shadows on nearby growth, the results suggest that larger urban centers by and large promote growth for more proximate places of less than 250 thousand people. However, there is some evidence the largest urban areas cast growth shadows on proximate medium-sized metropolitan areas (population between 250 thousand and 1.5 million) and of spatial competition among small metropolitan areas. The weak evidence of growth shadows suggests a need for a broader framework in understanding population movements.