Transportation in San Diego–Tijuana occurs by various means. Though, in the four cities of San Diego, Tijuana, Tecate, and Rosarito Beach, the automobile serves as most important means of transportation. The international metropolitan region maintains an intricate highway infrastructure. As a large metropolitan area in Western North America, many roadways, including Interstates, State Routes, and Mexican Federal Highways, hold a terminus in the area. These roads have grown accustomed to support the masses of the commuting populace within the international region and are constantly being expanded and/or renovated. Transportation is a crucial issue in the metropolitan area. The streets and highways of the region affect environmental health and have influence over the degree of regional conne