Shortly after Donald Trump’s election there was a deluge of commentary reminding us all that Trump’s presidency is “not normal.” To be sure, the president’s careless attitude towards the truth, his unorthodox communication style, not to mention his ignorance of how government works is rather irregular. Yet Trump’s campaign pledge to establish a “deportation force,” and his passion for domestic surveillance are hardly unprecedented in American history. A fleeting glance over the last century reminds us that America has experienced mass deportations and incarcerations before, whether prompted by domestic terrorism or military assault. What is new are the plethora of data available to law enforcement that makes deportations and mass surveillance easier to conduct.

Late in the evening of June 2, 1919 a bomb exploded outside Attorney General A. Mitchell Palmer’s home in Washington, D.C. The blast blew out windows within a one hundred yard radius and ejected homeowners from their beds. One of Palmer’s neighbors, Franklin Delano Roosevelt, had recently returned from a dinner party with his wife and ran across R Street to check on the Palmers. Carlo Valdinoci, an Italian anarchist and wannabe assassin, accidentally detonated the bomb early, and his remains were now scattered around the neighborhood—his torso ending up on a cornice on S Street, his scalp finding its way to a rooftop, and another part of his body flying through the window of the Norwegian ambassador’s residence. Copies of the anarchist pamphlet Plain Words were strewn across the area.

That wasn’t the only bombing that evening. Bombs were sent to officials in eight cities, but the only person killed, aside from Valdinoci, was a night watchman outside the home of New York judge Charles Cooper Nott.

The June attacks came only a few months after a string of other attempted mail bombings, all of which failed to kill their targets. Nonetheless, one of these bombs did blow off the hands off a maid working for ex-senator Thomas Hardwick. Newspaper reports and much of the public, already in the midst of the “Red Scare,” were quick to blame anarchists, Bolsheviks, and other “radicals.”

Speaking a few years later at a Senate Judiciary Committee hearing, Palmer said, “I remember […] the morning after my house was blown up, I stood in the middle of the wreckage of my library with Congressmen and Senators, and without a dissenting voice they called upon me in strong terms to exercise all the powers that was possible to the Department of Justice to run to earth the criminals who were behind that kind of outrage.”

Palmer began seeking out radicals such as anarchists and communists. At a meeting only two weeksafter the June bombings Palmer, a newly appointed assistant attorney general Francis P. Garvan, and Bureau of Investigation (BI) director William J. Flynn decided that mass deportation of radical aliens was required. They also made plans to establish the General Intelligence Division (GID), initially called the Anti-Radical Division. Garvan knew someone who would be ideal to run GID: a twenty-four year old named J. Edgar Hoover.

Hoover had been working for the Department of Justice for two years, but he started out in the unassuming position of librarian in the Library of Congress. That job “trained [him] in the value of collating material.” As Hoover would later write, “It gave me an excellent foundation for my work in the FBI where it has been necessary to collate information and evidence.” Hoover was somewhat modest about his cataloguing skills; his superiors at the Library were so impressed by his abilities that they doubled his pay.

As head of GID, Hoover was a librarian of sorts, establishing an index card database of “radicals.” By 1921, that database included about 450,000 names. Hoover’s library of radicals was used assist what came to be known as the “Palmer Raids.” The first of these raids took place on November 7, 1919, the second anniversary of the Russian revolution. BI agents and local police targeted the Union of Russian Workers in twelve cities.

As a result of the “Palmer Raids” 556 people were deported and around 10,000arrested, many without warrants. There would undoubtedly have been more deportations if Assistant Secretary of Labor Louis Freeland Post had not stepped in. Post, no fan of Palmer’s agenda, opened an investigation into the raids. At the time, the Department of Labor was responsible for deportations, and in April 1920 Post canceled 1,141 of the remaining 1,600 deportation orders.

Hoover did much more than oversee an extensive index card system, as Curt Gentry outlined in his book, J. Edgar Hoover: The Man and the Secrets:

Local police were encouraged to set up their own “Red squads” and share their findings with Washington. Private detective agencies, employed by the struck companies, supplied huge lists of names. Under a variety of pretexts—which included purchase, seizure, and theft—whole radical libraries were obtained. Newspapers were collected “by the bale” and pamphlets “by the ton.” Forty multilingual translators searched foreign-language periodicals for names and inflammatory quotations. Stenographers were sent to public meetings to take down the content of speeches. In Washington one-third of the BI’s special agents were assigned to antiradical work; in the field, over one-half, many of them undercover.

Despite criticism, Palmer consistently defended the raids . Two days before leaving the Department of Justice, Palmer told the Senate Judiciary Committee:

I apologize for nothing that the Department of Justice has done […] I glory in it. I point with pride and enthusiasm to the results of that work; and if […] some of the agents of the Department of Labor were a little rough and unkind, or short or curt, with these alien agitators whom they observed seeking to destroy their homes, their religion, and their country, I think it might well be overlooked in the general good to the country which has come from it. That is all I have to say.

America’s first “Red Scare” is far from the only time that federal authorities have used massive data collection to round up targets. Indeed, one of the most shameful episodes in American history was aided by such collection.

On December 7, 1941 the Imperial Japanese Navy Air Service attacked the U.S. naval base at Pearl Harbor. On February 19, 1942, more than two decades after he rushed across R Street to check on Palmer, President Franklin Delano Roosevelt signed Executive Order 9066, authorizing the internment of people of Japanese descent, including American citizens.

Roughly 120,000 people were put into internment camps. The early detention of these people was aided in part by Department of Justice data. The Department of Justice had been keeping tabs on particularpeople with Japanese ancestrysince the late 1930s. The Census Bureau also aided the internment, creating records of Japanese Americans. The internment continued despite a report written by naval intelligence officer Kenneth Ringle that found only a small fraction of Japanese aliens or citizens posed a threat to national security and that most of those were already in custody or members of well-known groups.

The Supreme Court ruled upheld Japanese internment as constitutional in the infamous 1944 case Korematsu v. United States, which has yet to be overturned.

Today, federal authorities have access to intelligence tools that would astonish Hoover, Palmer, and Roosevelt. This is of particularly acute concern at a time when the president is an unambiguous fan of domestic surveillance and has called for a “deportation force.” Such ambitious policies will require access to enormous amounts of data to be effective.

Now, thanks to tools such as Immigration and Customs Enforcement’s Investigative Case Management (ICM), the Trump administration has the means to carry out the mass deportations Trump promised us during his campaign, as The Intercept’s Spencer Woodman explained:

ICM allows ICE agents to access a vast “ecosystem” of data to facilitate immigration officials in both discovering targets and then creating and administering cases against them. The system provides its users access to intelligence platforms maintained by the Drug Enforcement Administration, the Bureau of Alcohol, Tobacco, Firearms and Explosives, the Federal Bureau of Investigation, and an array of other federal and private law enforcement entities. It can provide ICE agents access to information on a subject’s schooling, family relationships, employment information, phone records, immigration history, foreign exchange program status, personal connections, biometric traits, criminal records, and home and work addresses.

ICM isn’t the only piece of equipment that allows law enforcement to gather and analyze personal data. Half of American adults are in some kind of law enforcement facial recognition network, and police are increasingly using drones and cell-tower simulators, both of which enhance law enforcement’s ability to conduct surveillance.

The Palmer Raids and the internment of Japanese Americans are only a few examples of how terrifying attacks, whether they’re letter bombs or a coordinated military assault, can prompt the government to on trample on civil liberties. If history is any guide we should expect a similar response to the next attack, regardless of who the perpetrators might be.

We should also expect federal law enforcement priorities to shift. Early 20th century radicals and Japanese Americans are only two groups in a long list of government surveillance targets that includes folk singers, the ACLU, civil rights leaders, pacifists, Quakers, and others. For now, Muslims and illegal immigrants are the current administration’s immigration and law enforcement priorities. No one knows who’s next.

Fortunately, mass data collection of innocent people doesn’t have to be treated as inevitable. Reforms could require that federal agents must establish individual reasonable suspicion of a criminal violation before querying a law enforcement database. Allowing federal law enforcement to scour through databases during the next “Red Scare” or “War on Terror” will only facilitate more civil liberty violations. As the Trump administration violates civil liberties in the name of law enforcement and national security we shouldn’t forget that, regrettably, such violations are by no means unprecedented.