From the Gulf of Mexico it follows the course of the Rio Grande (Río Bravo del Norte) to the border crossing at El Paso, Texas, and Ciudad Juárez, Chihuahua. Westward from there it crosses vast tracts of the Sonoran and Chihuahuan Desert. Then it crosses the Colorado River Delta, west to San Diego and Tijuana before reaching the Pacific Ocean. The US-Mexican border is considered an open border.