In 1875 Congress started passing laws limiting immigration. By an Act of March 3, convicts and immoral women were denied entry. The immigration statute of August 8, 1882, forbade the admission of idiots, lunatics, convicts, and persons who might become a public charge. The first Chinese exclusion law was passed that same year, and in 1885 some foreigners were denied entry on the bases of a contract-labor law. Subsequently, many of these individuals sought admission by illegal means, usually by slipping around the entry points. Thus evolved the need for a border-control force. Congress instituted a Bureau of Immigration in 1885, and in 1903 transferred its tasks to the Department of Commerce and Labor. In 1904 a small group of mounted inspectors, usually called Mounted Guards or Chinese Immigration Agents, operated out of El Paso. Though they never totaled more than seventy-five, they patrolled as far west as California trying to restrict the flow of illegal Chinese immigration. In those days, once an undocumented immigrant had slipped past the Mounted Guards and entered the country, no officers existed to seek out and expel them. 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 cars and even boats. Although these inspectors had broader arrest authority, they still largely pursued Chinese. The undocumented immigrants disembarked on the Mexican west coast, walked overland to central Mexico, and rode the Mexican Central Railroad to the border town of Juárez, Chihuahua. From there they were smuggled into El Paso and thence to various parts of the nation. Before the Immigration Act of 1917, almost no restrictions were in effect against Mexicans or Canadians, who could cross at will and go anywhere they wished. After 1917, however, both Canadians and Mexicans paid a head tax of eight dollars to immigrate into the United States. They also had to pass a literacy test. After this restriction, illegal entries from these countries began and flourished until the arrival of troops along the border during the Mexican Revolution and World War I (1910–20). When the war ended and the soldiers went home, prohibited crossings accelerated again.
On May 28, 1924, Congress, under authority of the Immigration Act, established the United States Border Patrol as part of the Immigration Bureau, an arm of the Department of Labor. The uniformed agency, started in El Paso, was funded by $1 million and employed 450 officers. Its duties called for the prevention of smuggling, as well as the arrest of unauthorized entrants into the United States. Mounted Guards, policemen, Texas Rangers, sheriffs, and appointees from the Civil Service Register of Railroad Mail Clerks were employed. Congress authorized the border patrol in 1925 to assume authority over coastal operations as well as land, paying attention in particular to traffic from Cuba. Undocumented travelers and smugglers had been infiltrating Florida as well as the Gulf coast. The government initially provided the agents only a badge and revolver; the uniforms did not arrive until 1928. Recruits furnished their own horse and saddle, but Washington supplied oats and hay and paid the patrolmen $1,680 annually. In 1932 the patrol was placed under the authority of two directors, one in charge of the Mexican border office at El Paso, the other in charge of the Canadian border office at Detroit. Most undocumented immigrants from Mexico came only to visit their families or to work briefly in border towns. During Prohibition smuggling was a worse threat that absorbed most of the attention of the border patrol. Whiskey bootleggers avoided the bridges and slipped their forbidden cargo across the Rio Grande by way of pack mules. In intercepting these smugglers, more than one border patrolman laid down his life in dark, swampy thickets beside the river.
In 1933, President Franklin D. Roosevelt united the Bureau of Immigration and the Bureau of Naturalization into the Immigration and Naturalization Service. The first border patrol academy opened as a training school at Camp Chigas, El Paso, in December 1934. Thirty-four trainees attended classes in marksmanship and horsemanship. A patrolman was not considered a horseman until he had ridden up the rugged, nearby Mount Cristo Rey. Then he had to descend, still mounted. Although horses remained the transportation of choice for many years, by 1935 the border patrol had begun installing radios in vehicles and stations. The workload and accomplishments of the force remained fairly constant until 1940, when the patrol moved out of the Department of Labor to the Department of Justice and was beefed up by 712 additional patrolmen, 57 auxiliary personnel, and added equipment; the force now employed 1,531 officers. By the end of the war, employees numbered 8,000. The force provided tighter control of the border, manned alien detention camps, guarded diplomats, and assisted the coast guard in searching for Axis saboteurs. For the first time, the border was patrolled by air.
The McCarran-Walter Act of 1952 established the immigration laws in effect today. The same year, border patrol officers were first permitted to board and search a conveyance for undocumented immigrants anywhere in the United States. Unauthorized entrants traveling within the country were for the first time subject to arrest. In 1955 the INS split into four regional offices managed by commissioners who supervised district and border patrol sectors. During the war years and into the 1960s, while many men were absent from farms, a labor shortage developed. Farmers needed help, so the border patrol recruited Mexican nationals, called Braceros, authorizing them to visit the United States for specific periods of time as legal agricultural workers (see BRACERO PROGRAM). However, the program had serious side effects. Illegal immigration soared as those not chosen as Braceros sought to enter the country anyway. Furthermore, with the phasing out of the program, many former Braceros simply turned around in Mexico and crossed the Rio Grande illegally back into the United States. As illegal immigration roared out of control along the Mexican border, sixty-two Canadian border units were transferred south for Operation Wetback, a large repatriation project. The government air-lifted 52,000 undocumented immigrants into the Mexican interior, but the program died in 1952 after running out of funds during its first year. The Mexican government then offered train rides into the interior for nationals being returned from the San Antonio and Los Angeles districts. This program flopped after five months. Throughout the early 1950s a special task force of 800 border patrol officers was assigned by the United States attorney general to southern California, where thousands of Mexican nationals were rounded up and shipped home and thousands more left voluntarily. The task force moved to the lower Rio Grande valley, then to Chicago and other interior cities. Again, in spite of major successes in repatriation, many of deportees simply turned around and recrossed the seriously undermanned border. On September 8, 1954, the border patrol began expelling adult Mexican males by boat-lift from Port Isabel, Texas, to Veracruz. The project was discontinued two years later after nearly 50,000 Mexican nationals had been returned home. Various other flights, train trips, and bus trips originated along the border and terminated in the interior. Though partially successful, they also were expensive and were phased out primarily because of costs. Furthermore, by that time unauthorized migrants had begun entering on private aircraft. In cooperation with other federal services, the border patrol began tracking suspect flights. In 1958 the El Paso office of the border patrol established a Fraudulent Document Center that was afterward moved to Yuma. During the Cuban missile crisis of the early 1960s, Cuban defectors living in Florida flew aircraft out over the ocean in an effort to harass their former homeland. The American government made this harassment illegal, and assigned the border patrol to prevent unauthorized flights. The patrol added 155 officers, but discharged 122 of them when the crisis ended in 1963. The early sixties also witnessed aircraft-hijacking attempts by various psychopaths, and President John F. Kennedy ordered border patrolmen to accompany domestic flights and prevent takeovers. The Miami sector of the border patrol coordinated the effort. By that time the old business of human trafficking began to involve drug smuggling. The border patrol assisted other agencies in intercepting illegal drugs from Mexico.
The border patrol of the 1990s carries out its functions with a variety of devices, including helicopters, blimps, airplanes, radar, floodlights, motion detectors, cameras, informants, dogs, various vehicles, and fences and walls. Its duties are divided into several categories. A linewatch does surveillance of the border and apprehends illegal crossers when they enter. A farm and ranch check involves evaluating farms and ranches, which employ a broad variety of workers, many of them transient. Traffic checks are twenty-four-hour-a-day checkpoints along highways, where traffic is stopped and drivers are asked to prove their citizenship. Such checks lead to the frequent arrest of wanted criminals as well as the confiscation of tons of drugs. In city patrol, officers cruise various communities on foot or in vehicles seeking undocumented immigrants. Finally, in the function of transportation check, agents constantly monitor buses, trains, and airports for undocumented immigrants. In the 1990s, as the American public demands tighter control of the borders, the border patrol was again expanding and upgrading. The agents, highly trained and motivated, are taught Spanish. A significant percentage are of Hispanic origin.