After Chicago police officers shot a 20-year-old man on Sunday, reportedly after he shot at them — he was charged with attempted murder on Tuesday —  a tense scene broke out in Englewood. Tribune photographer Armando L. Sanchez captured a shot of dozens of officers packed inside the police tape at 57th and Aberdeen. When a rumor spread on social media that the victim was 15, not 20, the situation deteriorated; the same social channels were used to organize looting on Michigan Avenue as Sunday turned into Monday.

At 5 p.m. Monday, the mayor announced a return of the extreme lockdowns implemented after the unrest in May: a cordon sanitaire downtown from 8 p.m. to 6 a.m., allowing only residents and employees to enter the Loop by showing identification at specific access points. She also raised multiple bridges and shut down CTA trains (but not buses) throughout the city’s core.

If that sounds unusual, that’s because it is. The mass restriction of entire neighborhoods or cities by police in the United States is a recent development. According to a 1968 Yale Law Review article on the curfews implemented during the riots following Martin Luther King, Jr.’s death that spring, “the imposition of curfews on entire urban populations” was, at the time, “nearly unprecedented in American history.” The author could only find three curfews of entire populations before the 1960s, though ones of certain ages or races have more precedent. Of the 1968 curfew, only three were “preventative,” and “only a few” limited just parts of the city.

During the Miami riots of 1980, the city shut down both neighborhoods and transit. “Barriers were erected around the 20-square-mile predominantly black neighborhood of northwest Miami, to prevent whites from entering,” the Washington Post reported at the time. Buses were shut down in the riot area and all schools were closed, as were gas stations in all of the Liberty City neighborhood.

But those were immense and violent riots, leaving 18 dead and hundreds of buildings destroyed. A more immediate precedent is the curfew implemented in Dallas in late May and early June. Officials required residents of several neighborhoods in the city center, including downtown, to show proof that they live or work there in order to gain access. Lightfoot insists that her version is “NOT a curfew,” because residents and workers are allowed out during its imposition, but it’s functionally similar.

While there’s precedent for cutting off entire neighborhoods during extreme unrest, this kind of crowd-control creep has its roots in the infamous World Trade Organization protests in Seattle in 1999, just as today’s protest movements of all kinds are indebted to that event. As Gregory Scruggs writes for CityLab, Seattle police “allowed the protesters to block intersections at the front door of the convention center, and then used heavy-handed riot police tactics to disperse them. Big-city police have since learned from the Seattle Police Department’s failures 20 years ago: It’s a big reason why protesters today are quarantined in ‘free speech zones’ miles away from their targeted event.”

Protesters shut down the WTO meetings. They didn’t shut down the Free Trade Area of the Americas meeting in Miami in 2003, when what’s become known as the Miami model demonstrated the lessons police learned from the Seattle fiasco. Miami police cordoned off the area of the city around the FTAA meeting, checking credentials for access. The FTAA went on uninterrupted, and the city’s heavy-handed approach was viewed as a success by law enforcement. (John Timoney, who designed the response as the city’s police chief, was hired in 2011 by Bahrain’s interior ministry following its heavily criticized response to Arab Spring protests.)

The “soft hat” alternative to the “hard hat” Miami model is “command and control" — not as aggressive, but following similar principles. Both have also been augmented by post-9/11 approaches and technologies, and they’re not unique to the United States. Sociologist Alex Vitale observes similar approaches to the control of space from European and Canadian police. In France, sociologist Christian Mouhanna notes that police commonly cordon off entire neighborhoods as a “proactive” strategy; the country has also been going through its own reckoning over policing, one reason protests following the death of George Floyd were as large there as in many American cities.

In short, Chicago’s reaction to Sunday’s looting was both kind of new and kind of not. Such neighborhood cordons have happened before, but in this case it was unusually swift and in response to comparatively small-scale disorder — certainly compared to 1968, and even compared to earlier this year. If social conditions and social media don’t improve in the near future, such quickly implemented cordons could become a more common part of urban life.