Extending from Southern California to West Texas, the US-Mexico border is the most frequently crossed border in the world. The surrounding region was redefined by treaties of the 19th century, though ongoing disputes over territory and resources prompted the founding of the US Border Patrol in 1924. Its mission remains largely unchanged: to prevent the illegal entry of immigrants.
Communities on both sides of the border have become conflict flash points, staging grounds for passage and first stops on the other side. Many seeking to enter the US legally meet stiff closures, and crossing illegally incurs ever greater risks.