Tijuana is in Northwestern Mexico.
Tijuana ( [ tiːˈwɑːnə ] ; [ tiˈxwana ] ) is the largest city in Baja California and on the Baja California Peninsula and center of the Tijuana metropolitan area , part of the international San Diego -- Tijuana metropolitan area . As the city has become a leading center in the country , so has the surrounding metropolitan area , a major industrial and paramount metropolis in northwestern Mexico . Tijuana is the 45th largest city in the Americas and is the westernmost city in Mexico . The Tijuana River ( Río Tijuana ) is an intermittent river , 120 mi ( 195 km ) long , near the Pacific coast of northern Baja California state in northwestern Mexico and Southern California in the western United States . The Tijuana metropolitan area , and in Spanish the Zona Metropolitana de Tijuana , is located on the Pacific Ocean in Mexico .