SW-NCA-color-FINALweb

Climate Change and U.S.-Mexico Border Communities 343Figure 16.1 Western portion of the U.S.-Mexico border region. Source: EPA (2011).Most of the border’s population is concentrated along the international boundaryin fourteen city pairs (eight of them in the western portion) ii that constitute binationalurban systems. Rural population is scarce except for the irrigated areas of the ColoradoRiver and the Imperial-Mexicali valleys.The border region can be defined in a number of ways (Ganster and Lorey 2008;Varady and Ward 2009). These include the six Mexican and four U.S. border states, theregion of shared culture and language bisected by the border, the watersheds and subbasinsalong the boundary, the 62-mile zone (100 kilometers) on each side of internationalline as defined by the La Paz Agreement between Mexico and the United States,or by the administrative boundaries of the U.S. counties and the Mexican municipalities(municipos) that abut the international boundary. This chapter covers three U.S. states(California, Arizona, and New Mexico), the El Paso corridor, and three Mexican states(Baja California, Sonora, and Chihuahua). For present purposes, the latter category—border counties and municipios—is most important in terms of societal vulnerability toclimate change, given the border population concentration in major urban areas. Whilethe focus is on the region that includes the counties and municipalities along the border,data from these local administrative units are supplemented with state-level data.