After I handed in the first draft of my recent story about the takeover of the Baltimore City Detention Center by the Black Guerrilla Family gang, my editor had a suggestion/demand. It was good to quote the words of the inmates and the guards taken from government wiretaps, he said, but I should also go out and interview people who had done time inside B.C.D.C. What was it like for them?

The Maryland authorities had been fair about letting me tour the facility, but they wouldn’t allow me to go cell to cell, talking to detainees. So how would I find former inmates? Without much of a clue about what to do, I took the train back to Baltimore. When I arrived, I strolled down the row of cabs, leaning over to ask the drivers if they knew anyone who had done time in the jail. A half-dozen or so told me to go to hell, in various languages. When I was ready to give up this line of inquiry, a driver who had overheard my questions called me over and gave me some advice. “Walk about four blocks that way,” he said, pointing. “Turn left, and go to the McDonald’s. They’re all in there.”

So, without any other tips, I walked to Baltimore’s gritty North Avenue and found this standard-issue McDonald’s. It was late morning, pre-lunch, and there were a handful of guys nursing coffees. I sidled up to one and asked, “Do you know anyone who’s been in B.C.D.C.?”

“Yeah, me,” he said. I offered to buy him another coffee, and we began to talk. After a while, I approached another customer. He had been in the jail, too. Quickly, I changed my approach. Instead of asking if these folks knew anyone else who had been an inmate, I got right to the point: “Have you been inside B.C.D.C.?”

In the course of nearly two full days at the McDonald’s on North Avenue, roughly two-thirds of the men I approached had been inmates at B.C.D.C. All were African-American, as were virtually all the customers at the restaurant. It’s one thing to consult books like Michelle Alexander’s “The New Jim Crow” and read about the mass incarceration of African-Americans in the United States, but it’s another to see former prisoners filling the seats at a fast-food joint. Somehow the McDonald’s was even more shocking to me than B.C.D.C. itself, where virtually every inmate I saw was black. My informal McDonald’s survey brought home to me how ubiquitous the experience of being in jail is in certain parts of America.

Some of the men seemed to have turned their lives around. This part of Baltimore is slowly gentrifying, and there were several construction projects in the area. Some of the former inmates had found work on the sites and seemed to be doing fine. A customer named Aaron told me, “I was a good kid. I went to private school” before being arrested for assault, and said he was working construction and now regarded his jail stint as a distant memory. I also heard some crazy stories, which I knew could never be verified. One man claimed to be the father of a current N.B.A. star. A woman told me she had grown up in the same housing project as Tavon White, the leader of the Black Guerrilla Family in B.C.D.C. White is known to have fathered five children with four correctional officers in the jail, and this woman also claimed to have a child with him. Perhaps.

But there was no doubt that the McDonald’s customers were telling the truth about doing time at B.C.D.C. Their stories about the corruption and the gang control of the place were closely aligned. Several independently confirmed that the going price for a smuggled cell phone was three hundred dollars.

In the resulting piece, I quoted about a half-dozen former inmates, but, after a lot of coffee and burgers and fries, I had plenty more material. I imagined conducting a similar experiment at a McDonald’s in the suburbs—wandering up to random customers and asking if they had ever served time in the local jail. I expect that most, if not all, would have looked at me as if I were insane. But in Baltimore nobody was surprised by the question. And maybe I shouldn’t have been surprised by the answers.

Photograph by Stefan Ruiz