Most histories trace antiterrorism squads to the Haymarket bombing in Chicago in 1886, after which American police departments devoted a new zeal to gathering intelligence.

In 1904, the New York Police Department formed an Italian squad, and two years later the alien squad was created to contain a surge in immigrant crime.

Less than a decade after that, the bomb squad was deployed. Bolstered by surveillance and infiltration by federal agencies, the squad went on to focus on communists, socialists, anarchists, fascists, labor agitators, advocates of birth control and civil rights, antiwar protesters and other “enemies of government.”

As new enemies surfaced, the squad was re-branded as the radical squad, the neutrality squad, the red squad, the Bureau of Criminal Alien Investigation, the Bureau of Special Service Investigations and even the public relations squad. After Sept. 11, the demographics unit monitored Muslims.