Surveillance cameras on a light pole in the Englewood neighborhood of Chicago.CreditCreditAlyssa Schukar for The New York Times

Major European cities, including London, which may be the most surveilled city in the world, have long had networks of linked cameras. Now, in the United States, the technology race is on. Linked cameras are becoming commonplace in cities like New York and Baltimore. The Louisville police are considering using drones to respond to gunshots, and places like Orlando, Fla., and Washington County, Ore., are testing facial recognition software.

But advanced surveillance also presents the risk of intrusion and abuse, especially if it is carried out with little public disclosure or oversight. For example, it can be funded by federal grants that go directly to law enforcement without requiring local government approval. In February, Seattle began to dismantle a network of dozens of linked surveillance cameras and more than 150 wireless devices that the police had called vital in fighting crime, after complaints over their ability to covertly track cellphones.

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Either way, the police say they desperately need the help, and so far complaints have been muted. In recent years, the city has had more killings than Los Angeles and New York combined, but fewer than one in five homicides are solved.

Surveillance, the police say, is a game changer, with murder and gun violence significantly down this year.

The real test will come with warmer weather. Memorial Day weekend traditionally marks the start of the city’s most violent season. But in the May 4 shooting, the police were able to track down a suspect. Piecing together video from various cameras, including one that showed a man leaving his house shortly before the gunfire started, led to the arrest of Ernesto Godinez, 27.

The victim, who was assigned to an anti-gun task force, is expected to recover.

“The idea is to put technology in the hands of the officer,” Eddie T. Johnson, the city’s police superintendent, said. “Sometimes we arrive in time to see the guy still shooting.”

Early Saturday morning, the police posted on Twitter that they responded to a ShotSpotter alert, had an “armed encounter” and recovered a gun.

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The department tested the use of technology in two of its most violent areas in early 2017. When crime began to fall, the department ultimately set aside space in 13 of its 22 police stations for the surveillance centers, which tap into the city’s approximately 30,000 government-operated closed-circuit cameras.

Inside, civilian crime analysts from the University of Chicago Crime Lab — self-described “nerds” who are often learning data science on the fly — and uniformed officers work side by side at computer terminals, scrutinizing crime data as they search for trends.

Much of the technology is similar to equipment used by dozens of police departments around the nation: sensors to detect the location of gunshots, software designed to predict the time and location of crimes and license plate readers that photograph thousands of plates per minute.

What is different, the Chicago police say, is that the rooms allow the district’s crime data to be analyzed locally instead of at Police Headquarters, where neighborhood trends would not be as well understood.

There are also other factors that may be driving the decline in crime, criminologists say. The department has hired nearly 1,000 officers since January 2017 and overhauled its use-of-force and stop-and-frisk policies, which had contributed to community mistrust of the police. Establishing better community relationships is a priority, police leaders say.

“We need residents to tell us what’s going on,” said Kenneth Johnson, commander of the Englewood district since 2016. “I want them to feel comfortable talking. We’re taking baby steps. But all it takes is a questionable police shooting to tear that up.”

The police are calling Englewood, a poor, largely African-American neighborhood on the city’s South Side, a success story: Shootings are down by 52 percent compared with last year. Since the equipment was introduced in February 2017, the neighborhood has led the city in reduction of violent crime, the police say.

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It is still a place where tensions with the police are apparent. One recent afternoon, after a resident waved and asked how an officer was doing, the officer did not respond. Instead, he gave the man a dirty look before driving away.

But the new surveillance methods are regarded by residents as a largely positive development.

“It’s working. I think it is a wonderful resource to have technology to fight crime,” said Perry Gunn, executive director of Teamwork Englewood, a community organization focused on improving quality of life in the neighborhood.

Asiaha Butler, president of the Resident Association of Greater Englewood, said she had not heard a gunshot since January — the longest absence of gunfire she can remember in years. She believes both the surveillance and a greater emphasis by the police on improving community relations had helped push down crime.

“Before, beat officers wouldn’t say hello,” she said. “One even flipped me off a couple of years ago.”

The department has tried to demonstrate transparency by inviting community leaders like Ms. Butler to tour the strategic centers.

“When I first saw the room, it felt like surveillance,” Ms. Butler said. “But I also know the individuals who are doing it,” she continued, referring to those committing crimes. “There has to be a feeling like they are being watched. As long as the police focus on individuals who are repeat offenders — robbing people on the block or shooting people — I’m O.K. with that.”

Even with 120 to 150 police cameras in the district — and more on the way — Mr. Johnson, the district commander, said the level of surveillance is not unreasonable.

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“First, let’s use the strategy and technology not to harm the community,” he said. “This isn’t a secret. This isn’t an Orwellian ‘Big Brother.’”

But Kofi Ademola, a local activist, disagreed.

“There was not a conversation like, ‘Do you want this in your community?’ ” he said. “Instead, the Chicago police say, ‘This is in your community and it is going to cut crime,’ and unfortunately, people don’t question that. It’s now been normalized for these communities to be under constant surveillance, which contributes to the criminalization of people. It is problematic.”

The room’s computer screens display the location of every police car in the district. Clicking on the icon of a police car brings up information related to the 911 call the officer is responding to. Another click produces the location of nearby surveillance cameras. Officers can also commandeer the camera to get a 360-degree view of the area.

Other maps show the gang territories of groups with names like the Rubenites and Halsted Boys Entertainment, sometimes covering a mere two or three impoverished blocks.

The civilian analysts spend much of their time feeding a range of information into software called HunchLab, which considers a number of variables — from gang tensions and gunshot reports to the number of parolees living in an area — to forecast crime by giving probability scores, much like a meteorological report.

HunchLab also examines less obvious data points, like the location of liquor stores and schools, an area’s proximity to local expressways, and even weather conditions and phases of the moon (there is more crime during full moons; no one knows why).

If an officer makes an arrest and the person has a prior record, a photograph and more data, including tattoos and an address, is sent to the officer’s smartphone.

One officer, surprised to be receiving so much information, announced over the radio: “I don’t know who is telling me all this, but keep it coming!”