Population in Trans-Border Regions: The Southern California-Baja California Urban System 1

This article is a case study of population growth and composition in the Southern California-Baja California trans-border urban system (TBS). The central question guiding the research is how the combination of geographic proximity and economic integration in two very different regions affects population characteristics in the Southern California-Baja California TBS. We begin by briefly defining trans-border urban systems. We then specify the attributes of the Southern California-Baja California TBS, contrasting them with attributes observed elsewhere in the United States and Mexico. We particularly emphasize the impact of the Mexican-origin population on population growth, composition, age structure and trans-border mobility. We conclude by outlining several national and international policy implications that can be derived from a regional focus on the Southern California-Baja California TBS. The units of analysis are the aggregate TBS and the component counties and municipios. The data are drawn primarily from the U.S. and Mexican censuses. Secondary data from a variety of sources also are discussed.