In my experience, many people believe that New Yorkers are smarter than other Americans, and this may actually be true. The majority of people who live in New York City were not born here. Indeed, more than a third were not born in the United States. New Yorkers, then, are people who left another place and came here, looking for something, which suggests that the population is preselected for higher energy and ambition.

Also for a willingness to forgo basic comforts. I grew up in California, where even middle-income people have a patio on which they can eat breakfast and where almost everyone has a car. In New York, only upper-income people enjoy those amenities. The others would like to share them. I sometimes get into conversations with taxi drivers, and since most of them are new to the city, I often ask them what they miss about the place they came from. Almost always, they name very ordinary pleasures: a slower pace of life, a café where they could sit around and talk to friends, a street where they could play kickball without getting run over. Those who miss these things enough will go back home. That means that the rest of us, statistically, are more high-strung, hungry and intent on long-term gains—traits that quite possibly correlate with intelligence.

But I think it's also possible that New Yorkers just appear smarter, because they make less separation between private and public life. That is, they act on the street as they do in private. In the United States today, public behavior is ruled by a kind of compulsory cheer that people probably picked up from television and advertising and that coats their transactions in a smooth, shiny glaze, making them seem empty-headed. New Yorkers have not yet gotten the knack of this. That may be because so many of them grew up outside the United States, and also because they live so much of their lives in public, eating their lunches in parks, riding to work in subways. It's hard to keep up the smiley face for that many hours a day.

It is said that New Yorkers are rude, but I think what people mean by that is that New Yorkers are more familiar. The man who waits on you in the delicatessen is likely to call you sweetheart. (Feminists have gotten used to this.) People on the bus will say, "I have the same handbag as you. How much did you pay?" If they don't like the way you are treating your children, they will tell you. And should you try to cut in front of somebody in the grocery store checkout line, you will be swiftly corrected. My mother, who lives in California, doesn't like to be kept waiting, so when she goes into the bank, she says to the people in the line, "Oh, I have just one little thing to ask the teller. Do you mind?" Then she scoots to the front of the line, takes the next teller and transacts her business, which is typically no briefer than anyone else's. People let her do this because she is an old lady. In New York, she wouldn't get away with it for a second.

While New Yorkers don't mind correcting you, they also want to help you. In the subway or on the sidewalk, when someone asks a passerby for directions, other people, overhearing, may hover nearby, disappointed that they were not the ones asked, and waiting to see if maybe they can get a word in. New Yorkers like to be experts. Actually, all people like to be experts, but most of them satisfy this need with friends and children and employees. New Yorkers, once again, tend to behave with strangers the way they do with people they know.

This injects a certain drama into our public life. The other day I was in the post office when a man in line in front of me bought one of those U.S. Postal Service boxes. Then he moved down the counter a few inches to assemble his package while the clerk waited on the next person. But the man soon discovered that the books he wanted to mail were going to rattle around in the box, so he interrupted the clerk to tell her his problem. She offered to sell him a roll of bubble wrap, but he told her that he had already paid $2.79 for the box, and that was a lot for a box—he could have gotten a box for free at the liquor store—and what was he going to do with a whole roll of bubble wrap? Carry it around all day? The clerk shrugged. Then the man spotted a copy of the Village Voice on the counter and laid hold of it to use it for stuffing. "No!" said the clerk. "That's my Voice." Annoyed, the man put it back and looked around helplessly. Now a woman in line behind me said she'd give him the sections of her New York Times that she didn't want, and she began going through the paper. "Real estate? You can have real estate. Sports? Here, take sports." But the real estate section was all the man needed. He separated the pages, stuffed them in the box and proceeded to the taping process (interrupting the clerk once again). Another man in line asked the woman if he could have the sports section, since she didn't want it. She gave it to him, and so finally everything was settled.

This was an interesting show, to which you could have a wide range of reactions. Why didn't the box man bring some stuffing? If the clerk hadn't finished her Village Voice, why did she leave it on the counter? And so on. In any case, the scene sufficed to fill up those boring minutes in line—or, I should add, to annoy the people who just wanted to read their newspaper in peace instead of being exposed to the man's postal adventure. I won't say this could happen only in New York, but I believe that the probability is much greater here.

Why are New Yorkers like this? It goes against psychological principles. Psychologists tell us that the more stimuli people are bombarded with, the more they will recede into themselves and ignore others. So why is it that New Yorkers, who are certainly confronted with enough stimuli, do the opposite? I have already given a few possible answers, but here's one more: the special difficulties of life in New York—the small apartments, the struggle for a seat on the bus or a table at a restaurant—seem to breed a sense of common cause. When New Yorkers see a stranger, they don't think, "I don't know you." They think, "I know you. I know your problems—they're the same as mine—and furthermore we have the same handbag." So that's how they treat you.

This belief in a shared plight may underlie the remarkable level of cooperation that New Yorkers can show in times of trouble. Every few years or so, we have a water shortage, and then the mayor goes on the radio and tells us that we can't leave the water running in the sink while we're brushing our teeth. Surprise! People obey, and the water table goes up again. The more serious the problem, the more dramatic the displays of cooperation. I will not speak of the World Trade Center disaster, because it is too large a subject, but the last time we had a citywide power failure, and hence no traffic lights, I saw men in business suits—they looked like lawyers—directing traffic at busy intersections on Ninth Avenue. They got to be traffic cops for a day and tell the big trucks when to stop and when to go. They looked utterly delighted.

Another curious form of cooperation one sees in New York is the unspoken ban on staring at celebrities. When you get into an elevator in an office building and find that you are riding with Paul McCartney—this happened to me—you are not supposed to look at him. You can peek for a second, but then you must avert your eyes. The idea is that Paul McCartney has to be given his space like anyone else. A limousine can bring him to the building he wants to go to, but it can't take him to the 12th floor. To get there, he has to ride in an elevator with the rest of us, and we shouldn't take advantage of that. This logic is self-flattering. It's nice to think that Paul McCartney needs us to do him a favor, and that we live in a city with so many famous people that we can afford to ignore them. But if vanity is involved, so is generosity. I remember, once, in the early '90s, standing in a crowded lobby at City Center Theater when Jackie Onassis walked in. Everyone looked at her and then immediately looked down. There was a whole mob of people staring at their shoes. When Jackie died, a few years later, I was happy to remember that scene. I was glad that we had been polite to her.

Of course, the rule with celebrities, which forbids involvement, is different from the other expressions of common cause, which dictate involvement. And since few of us are celebrities, the latter are far more numerous. As a result, New Yorkers, however kind and generous, may also come off as opinionated and intrusive. Living with them is a little like being a child again and having your mother with you all the time, helping you, correcting you, butting into your business. And that, I believe, is another reason why New Yorkers seem smarter. Your mother knew better, too, right?

Joan Acocella is a staff writer for The New Yorker.

Photographer Bob Sacha is based in New York City.