It was not always a crime to enter the United States without authorization.

In fact, for most of American history, immigrants could enter the United States without official permission and not fear criminal prosecution by the federal government.

That changed in 1929. On its surface, Congress’snew prohibitions on informal border crossings simply modernized the U.S. immigration system by compelling all immigrants to apply for entry. However, in my new book “City of Inmates,” I detail how Congress outlawed border crossings with the specific intent of criminalizing, prosecuting and imprisoning Mexican immigrants.

Knowing this history is important now. On April 11, 2017, U.S. Attorney General Jeff Sessions announced his plan to step up prosecutions of unlawful entries, saying it’s time to “restore a lawful system of immigration.” This may read like a colorblind commitment to law and order. But the law Sessions has vowed to enforce was designed with racist intent.

The Mexican immigration debate

The criminalization of informal border crossings occurred amid an immigration boom from Mexico.

In 1900, about 100,000 Mexican immigrants resided in the United States.

By 1930, nearly 1.5 million Mexican immigrants lived north of the border.

As Mexican immigration surged, many in Congress were trying to restrict non-white immigration. By 1924, Congress had largely adopted a “whites only” immigration system, banning all Asian immigration and cutting the number of immigrants allowed to enter the United States from anywhere other than northern and western Europe. But whenever Congress tried to cap the number of Mexicans allowed to enter the United States each year, southwestern employers fiercely objected.

U.S. employers had eagerly stoked the era’s Mexican immigration boom by recruiting Mexican workers to their southwestern farms, ranches and railroads, as well as their homes and mines. By the 1920s, western farmers were completely dependent on Mexican workers.

However, they also believed that Mexican immigrants would never permanently settle in the United States. As agribusiness lobbyist S. ParkerFrisselle explained to Congress in 1926, “The Mexican is a ‘homer.’ Like the pigeon he goes home to roost.” On Frisselle’s promise that Mexicans were “not immigrants” but, rather, “birds of passage,” western employers successfully defeated proposals to cap Mexican immigration to the United States during the 1920s.

The idea that Mexican immigrants often returned to Mexico contained some truth. Many Mexican immigrants engaged in cyclical migrations between their homes in Mexico and work in the United States. Yet, by the close of the 1920s, Mexicans were settling in large numbers across the southwest. They bought homes, started newspapers, churches and businesses. And many Mexican immigrants in the United States started families, raising a new generation of Mexican American children.

Monitoring the rise of Mexican American communities in southwestern states, the advocates of a whites-only immigration system charged western employers with recklessly courting Anglo America’s racial doom. As the work of historian Natalia Molina details, they believed Mexicans were racially unfit to be U.S. citizens.

Western employers agreed that Mexicans should not be allowed to become U.S. citizens. “We, in California, would greatly prefer some set up in which our peak labor demands might be met and upon the completion of our harvest these laborers returned to their country,” Friselle told Congress. But western employers also wanted unfettered access to an unlimited number of Mexican laborers. “We need the labor,” they roared back at those who wanted to cap the number of Mexican immigrants allowed to enter the United States each year.

Amid the escalating conflict between employers in the West and advocates of restriction in Congress, a senator from Dixie proposed a compromise.

Blease’s Law

Sen. Coleman Livingston Blease hailed from the hills of South Carolina. In 1925, he entered Congress committed, above all else, to protecting white supremacy. In 1929, as restrictionists and employers tussled over the future of Mexican immigration, Blease proposed a way forward.

According to U.S. immigration officials, Mexicans made nearly 1 million official border crossings into the United States during the 1920s. They arrived at a port of entry, paid an entry fee and submitted to any required tests, such as literacy and health.

However, as U.S. immigration authorities reported, many other Mexican immigrants did not register for legal entry. Entry fees were prohibitively high for many Mexican workers. Moreover, U.S. authorities subjected Mexican immigrants, in particular, to kerosene baths and humiliating delousing procedures because they believed Mexican immigrants carried disease and filth on their bodies. Instead of traveling to a port of entry, many Mexicans informally crossed the border at will, as both U.S. and Mexican citizens had done for decades.

When the debate stalled over how many Mexicans to allow in each year, Blease shifted attention to stopping the large number of border crossings that took place outside ports of entry. He suggested criminalizing unmonitored entry.

According to Blease’s bill “unlawfully entering the country” would be a misdemeanor, while unlawfully returning to the United States after deportation would be a felony. The idea was to force Mexican immigrants into an authorized and monitored stream that could be turned on and turned off at will at ports of entry. Any immigrant who entered the United States outside the bounds of this stream would be a criminal subject to fines, imprisonment and ultimately deportation. But it was a crime designed to impact Mexican immigrants, in particular.

Neither the western agricultural businessmen nor the restrictionists registered any objections. Congress passed Blease’s bill, the Immigration Act of March 4, 1929, and dramatically altered the story of crime and punishment in the United States.

Caged

With stunning precision, the criminalization of unauthorized entry caged thousands of Mexico’s “birds of passage.” By the end of 1930, the U.S. Attorney General reported prosecuting 7,001 cases of unlawful entry. By the end of the decade, U.S. Attorneys had prosecuted more than 44,000 cases.