Tijuana, Mexico (right)

The Mexico–United States barrier (Spanish: barrera México–Estados Unidos), also known as the border wall, is a series of vertical barriers along the Mexico–United States border intended to reduce illegal immigration to the United States from Mexico.[1] The barrier is not a continuous structure, but a series of obstructions classified as 'fences' or 'walls'.

Between the physical barriers, security is provided by a 'virtual fence' of sensors, cameras, and other surveillance equipment used to dispatch United States Border Patrol agents to suspected migrant crossings.[2] In May 2011, the Department of Homeland Security stated that it had 649 miles (1,044 km) of barriers in place.[3] The total length of the continental border is 1,954 miles (3,145 km).