On the way in from the airport, late one night, my taxi lowered into the Manhattan landscape and came to a stop at a red light at Ninety-seventh Street, just off Second Avenue. There is a playground there, and when I looked out the window I saw a man shooting a basketball by himself. The court was a barren, lonely place at that hour, lit by some nearby streetlights, but his presence redeemed it. He was a heavy man, dressed in grey sweats, and, for a moment, I imagined that he was a once-talented player who had gone to seed, now moved by some personal crisis to revisit his old skills near midnight.

After a moment of watching, it seemed clear that he had never had much in the way of skills. I then imagined that he had recently made a resolution to lose weight. He was moving quickly to get his own rebound, dribbling energetically, and I decided that this late-night cameo appearance signalled that he was in the manic phase of his resolution, that he was pushing himself too hard, that he would diet and work out like this for four days and then pull a muscle. By the end of the week, he would be eating pound cake out of the box.

For once, I was grateful for an interminable red light. The man was undaunted, rhythmic. His movements suggested some interior fantasy was in progress. I wondered what it was as the cab pulled away.

Location is important with basketball, and yet it’s not—you can play anywhere, and in the act of playing you forget where you are. I make a point of playing basketball whenever I travel to a new place. There is an outdoor court in Paradise Valley, Montana, that has stayed with me. And there is a hoop in a parking lot in Phnom Penh, next to an apartment building with balconies on which, as I shot around there, in 1994, little kids appeared. More and more of these kids materialized as my workout continued, all of them practicing their English, which seemed to consist of one word: “Hello.” They murmured it, softly at first, then louder. It was like playing in front of a flock of gently cooing birds that slowly, gradually, morphed into crazy American basketball fans, all of them shouting, “Hello!”

Basketball is a sport that contains many games. The one we watch on television is only one variation. Basketball can be played alone or in groups. Indoors or outdoors. Full court, half court, or no court. N.B.A. players who play abroad must adjust to the rules of the league’s European counterpart, FIBA (The famously taciturn Tim Duncan offered his two cents on this variation of the game at the end of the 2004 Olympics: “FIBA sucks.”) Was the guy I saw shooting around by himself in the dark on Ninety-Seventh street playing basketball? To quote a favorite phrase of the former Knick John Starks, “Most definitely.”

When another former Knick, Bill Bradley, ran for Senate in New Jersey, his television commercials ended with him tossing a crumpled piece of paper into a tiny basketball hoop affixed to a garbage pail. Is throwing something into a trashcan—with or without a tiny hoop attached—basketball? You could make the case. In the documentary “Doin’ It in the Park: Pick-Up Basketball, NYC,” made by Robert (Bobbito) García and Kevin Couliau, an old-timer in Harlem recalls seeing the local playground courts so crowded with serious players that the kids were forced into a kind of apprenticeship, in which they would shoot hoops into a garbage can off to the side.

The culture of New York City playground basketball looms large in the history of the N.B.A. Several generations of the game’s greatest players owe their basketball education, in part, to New York’s Department of Parks and Recreation. So it was appropriate that the N.B.A. used the occasion of the 2015 All-Star Game, which was played at Madison Square Garden, to commemorate this fact with a magnificently detailed map (and an app) titled “A History of New York City Basketball.” The map is filled with notable places, along with links to short videos. Each of the five boroughs has its own section, and the app featured special categories for “point guards” and “playgrounds.” It seems right that these subjects should be highlighted. Street ball and ball handling are entwined. New York is, or was, known for its fierce point guards. The video takes you through the history: Bob Cousy, Dick McGuire, Tiny Archibald, Pearl Washington, Rod Strickland, Kenny Smith, Kenny Anderson, Mark Jackson, Rafer Alston, Stephon Marbury, Jamaal Tinsley, Kemba Walker.

The segment on Manhattan is mostly focussed on the borough’s most famous product, introduced as perhaps the greatest player ever to play the game: Kareem Abdul-Jabbar. When he says, “I was raised in Manhattan, so I learned the game right in the heart of the city,” it is understood, even before the clip cuts away to a shot of the court at 140th Street and St. Nicholas Avenue, that he is referring to his local playground. “I never consciously made a connection between basketball and how it is tied to life in New York City,” he says, while the camera pans across the court in morning light. “But I grew up in it, and I was part of it.” The implication is that the playground is the primal scene of Abdul-Jabbar’s basketball initiation and education.

As much as I enjoyed the history lesson from the N.B.A., it further crystalized my feeling that this was a historical moment that has been eclipsed. Street ball in New York is in decline. I have observed, in the past decade, one playground after another—where, once, you could have shown up in the mid to late afternoon and found a group of fairly skilled players of different ages battling—become depopulated. I am not talking about a mass extinction. There are still lots of playgrounds with lots of good players—but fewer playgrounds, and fewer players, and the ones who show up seem older. Kareem’s playground, for example, had just a few desultory players shooting by themselves on a recent afternoon. A river that runs low will sometimes run dry.

That the basketball courts of New York’s playgrounds are not as populated as they once were is an observation based firmly on evidence that is anecdotal and totally unscientific. Furthermore, even this evidence is mostly limited to Manhattan. So perhaps these are all Manhattan problems. When I read a report in the Times on the people who buy condos in the Time Warner Center—in brief, extremely rich and not from here—I wasn’t thinking about basketball, but it now occurs to me that the Time Warner Center is less than ten blocks from the projects that provided a fair number of the players at my own childhood basketball court, in Riverside Park at 76th Street. Can billionaires play ball? That is a different city game.

I am not claiming that the city’s courts are empty, exactly—up on St. Nicholas Terrace, about ten blocks from where Kareem played, there was a respectable half-court game underway when I visited, but no one had next. One court over, however, was the scene of a roiling game of full court, comprised mostly of kids. The place was not abandoned, yet this was not the world of highly competitive basketball in which so many N.B.A. talents were forged. The courts on Horatio Street and Hudson (where Joakim Noah, age fourteen, a human pencil with an afro, dunked on me) are now devoid of pick-up basketball in the afternoons. That court had been closed for renovations for some time, so perhaps it’s a special case. The Tompkins Square Park courts are mostly empty; the courts on 20th and Second Avenue, where a lot of the Tompkins Square Park crowd sought refuge, are now barren.