Mounted watchmen of the United States Immigration Service patrolled the border in an effort to prevent illegal crossings as early as 1904, but their efforts were irregular and undertaken only when resources permitted. The inspectors, usually called “mounted guards”, operated out of El Paso, Texas. Though they never totaled more than 75, they patrolled as far west as California trying to restrict the flow of illegal Chinese immigration.
In March 1915, Congress authorized a separate group of mounted guards, often referred to as “mounted inspectors”. Most rode on horseback, but a few operated automobiles, motorcycles and boats. Although these inspectors had broader arrest authority, they still largely pursued Chinese immigrants trying to avoid the National Origins Act and Chinese Exclusion Act of 1882. These patrolmen were Immigrant Inspectors, assigned to inspection stations, and could not watch the border at all times. U.S. Army troops along the southwest border performed intermittent border patrolling, but this was secondary to “the more serious work of military training.” Non-nationals encountered illegally in the U.S. by the army were directed to the immigration inspection stations. Texas Rangers were also sporadically assigned to patrol duties by the state, and their efforts were noted as “singularly effective”.
The Border Patrol was founded on May 28, 1924 as an agency of the United States Department of Labor to prevent illegal entries along the Mexico–United States border and the United States-Canada border. The first two border patrol stations were in El Paso, Texas and Detroit, Michigan. Additional operations were established along the Gulf Coast in 1927 to perform crewman control to insure that non-American crewmen departed on the same ship on which they arrived. Additional stations were temporarily added along the Gulf Coast, Florida and the Eastern Seaboard during the sixties when in Cuba triumphed the Cuban Revolution and emerged the Cuban Missile Crisis.
Prior to 2003, the Border Patrol was part of the Immigration and Naturalization Service (INS), an agency that was within the U.S. Department of Justice. INS was decommissioned in March 2003 when its operations were divided between CBP, United States Citizenship and Immigration Services, and U.S. Immigration and Customs Enforcement.
The priority mission of the Border Patrol, as a result of the 9/11 attacks and its merging into the Department of Homeland Security (DHS) is to prevent terrorists and terrorist weapons from entering the United States of America. However, the Border Patrol’s traditional mission remains as the deterrence, detection and apprehension of illegal immigrants and individuals involved in the illegal drug trade who generally enter the United States other than through designated ports of entry. The Border Patrol also operates 33 permanent interior checkpoints along the southern border of the United States.
Currently, the U.S. Border Patrol employs over 20,200 agents (as of the end of fiscal year 2009), who are specifically responsible for patrolling the 6,000 miles (9,700 km) of Mexican and Canadian international land borders and 2,000 miles (3,200 km) of coastal waters surrounding the Florida Peninsula and the island of Puerto Rico. Agents are assigned primarily to the Mexico–United States border, where they are assigned to control drug trafficking and illegal immigration. Patrols on horseback have made a comeback since smugglers have been pushed into the more remote mountainous regions, which are hard to cover with modern tracking strategies.