WASHINGTON — As the school year draws to a close, the perennial worry about teenage misbehavior and how to keep youth occupied in the summer has a new name with ominous undertones: “teen takeovers.”

In Detroit, Chicago, Atlanta, the nation’s capital and elsewhere, large, quickly organized gatherings of youths have popped up in downtowns, parks and leafy neighborhoods. They can be noisy, boisterous and at times violent, their impact often amplified on television, especially in conservative media outfits like Fox News.

“It has gotten worse when it comes to the bad behavior,” Larry Snelling, the superintendent of the Chicago Police Department, said in an interview. “Kids just start to fight, so they get increasingly more violent.”

Societal anxiety over juvenile delinquency is not new. A family court judge told The New York Times in 1952, “The reasons for children getting into trouble are the same yesterday as forever — revolt, rebellion, the need for self-expression, denied to them somehow, in a natural way.” At that time, authorities attributed the “extreme behavior of youth” to the Korean War, national and international insecurity, and a lack of mental health treatment.

Now it’s social media and the long tail of COVID-19, with its resulting Zoom-from-home generation. But what is undeniably new is the role that platforms like Instagram and TikTok play in the speed of organization and the scale of assembly. And the larger the gatherings, the better the chance that something can go wrong.

“Detroit teens do have a thing for pulling out guns while fighting,” said Malaysia McCline, 15, who recalled stumbling into a teen takeover last month after the Detroit Tigers’ opening day.

She and friends had noticed a growing crowd at the city’s waterfront that included a former classmate she’d lost touch with. It was fun, but by nightfall, some became rowdier, yelling and running. Police officers moved in.

Law enforcement officials around the country are enjoying a period of good news. Crime overall in cities including Chicago, Houston, Los Angeles and Columbus, Ohio, has dropped significantly in recent years. Homicides nationally are poised to hit their lowest rate in more than a century, data shows, a remarkable recovery from pandemic highs.

But the pandemic exacerbated a decline in the amount of time that teenagers spend going out and socializing, and socializing is a natural impulse, said Laurence Steinberg, a psychology professor who studies adolescent development. It is bound to burst out.

Just what should be considered a teen takeover is nebulous. On May 3 near Oklahoma City, at least 23 people were injured in a shooting at what police labeled an “unsanctioned” lakeside party. Like classic takeovers, it had been advertised on social media and drew a large crowd of teens and people in their early 20s.