The United States Border Patrol (USBP) is an American federal law enforcement agency. Its mission is to detect and prevent illegal aliens, terrorists and terrorist weapons from entering the United States, and prevent illegal trafficking of people and contraband. The Border Patrol is one of the largest law enforcement agencies in the US with nearly 20,000 agents.

The primary mission of the Border Patrol is to protect our Nation by reducing the likelihood that dangerous people and capabilities enter the United States between the ports of entry. This is accomplished by maintaining surveillance, responding to electronic sensor alarms, aircraft sightings and interpreting and following tracks. Some of the major activities include maintaining traffic checkpoints along highways leading from border areas, conducting city patrol and transportation check, and anti-smuggling investigations.

Often, the border is a barely discernible line in uninhabited deserts, canyons, or mountains. The Border Patrol utilizes a variety of equipment and methods to accomplish its mission in such diverse terrain. Electronic sensors are placed at strategic locations along the border to detect people or vehicles entering the country illegally. Video monitors and night vision scopes are also used to detect illegal entries. Agents patrol the border in vehicles, boats, and afoot. In some areas, the Border Patrol even employs horses, all-terrain motorcycles, bicycles, and snowmobiles.