 The urbanized area where San Diego and Tijuana meet is known as San Ysidro on the American side of the border and Colonia Federal/Colonia Libertad on the Mexican side.East from the coast , the Tijuanense boroughs of Mesa de Otay and Centenario are heavy urbanized whereas the corresponding American area of Otay Mesa is composed of primarily dispersed industrial and distribution facilities.At the Pacific Ocean region of the border, the border is urbanized on the Mexican side while the adjacent American side is an estuarine preserve, and thus not urbanized.