 San Diego–Tijuana

San Diego–Tijuana is an international transborder agglomeration, straddling the border of the adjacent North American coastal cities of San Diego, California, United States and Tijuana, Baja California, Mexico.The 2012 population of the region was 4,922,723, making it the largest bi-national conurbation shared between the United States and Mexico, the third-largest shared between the US and another country, and the fourth-largest in the world.