Tijuana is in Southwestern 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 .