Here are two easy questions. What attracts people to a place? And what keeps them there?

Actually, these aren’t easy questions at all. There are many reasons a person might pack up and move to a new city: a job, an education, a change of lifestyle or climate, family connections, restlessness, curiosity, and so on. And what keeps a person in a place once she has arrived? Again, not a single reason. The job, family ties, inertia – and maybe a dozen other things.

So let’s ask these questions in a different way: What can local governments and others who care about cities do to make their communities more attractive to outsiders and binding to those already there? To use an economics term, where can you invest at the margins to increase a community’s attraction and appeal, to make it more of a magnet and give it more glue?

If you don’t like my analogies – magnet and glue – don’t blame me. I borrowed them from a book written in 1997 by Rosabeth Moss Kanter, a professor at the Harvard Business School. The book is “World Class: Thriving Locally in the Global Economy,” and these were the things Kanter said every city needed to be successful: a “magnet” to pull people in, and enough “glue” to keep them there.

What can cities do to be better magnets? They can’t do much about their climates or family connections, but they can have a big influence on their economies. The best ways are by building and maintaining good physical infrastructure, offering a skilled and educated work force, and constantly and creatively selling the community’s assets through economic development activities. So spend money on roads, sewers, and transit, invest in schools, and support your local chamber of commerce.

And glue? What can cities do to bind their citizens so tightly that even if their economic circumstances change (say, their employer closes shop), personal lives change (they retire, their kids move away), or neighborhood demographics change, they can’t bring themselves to leave – even with good options elsewhere? Answer: They can invest in quality of life.

But what is quality of life? Of all the phrases used in cities, this may be the slipperiest. For many, quality of life is what they personally like about their community, from a favorite senior center and concerts on the town square to low taxes and good public services. But actually, quality of life is important and specific – and, best of all, it’s something only cities can deliver. States can’t provide quality of life, neither can counties. Only organized, developed places can – which is to say, cities and towns.

To understand quality of life – and why only cities can provide it – you have to start by knowing its purposes. In my view, there are three: to offer connectedness with other people, to create a sense of place and identity, and to provide opportunities for personal growth. Let’s look at each.

Connectedness: One of the most basic human needs is for connection with others. We do this all our lives – in school, at work, at parties, in churches and synagogues, and, yes, at civic meetings – and many of us do it so unconsciously that we forget how hard it can be for others, especially newcomers. The good news is that cities, with their sidewalks and town squares, libraries, restaurants, shops and work places, are tailor made for bumping into people and exchanging greetings from a tip of the hat to a long conversation.

But just because they are natural meeting places doesn’t mean every city does it equally well. The best – the ones we think of as having the highest quality of life – are intentional about bringing together strangers safely and harmoniously. The primary ways are through events and public spaces. Events are anything that draws a crowd and provides opportunities for conversation – parades, festivals, block parties, civic meetings, and the like. Public spaces do pretty much the same thing. If you’ve ever had lunch in at a sidewalk café or on a park bench and struck up a conversation with the person next to you, you know how it works. And even if you’re not the sort who talks with strangers, sitting in a place where you can see your fellow citizens is reassuring. It gives you a sense of connection even without interaction. And that’s the point: People don’t easily leave places they feel connected with.

Identity: This is another basic human need, the sense of belonging, but the connection here is not to other people but to a place. If you’ve lived in different parts of the country you know the feeling: Sooner or later, you decide this is your kind of town or it’s not. It could be the architecture, the accents, the things people eat for breakfast, the way they drive their cars, or the pace of life. Some of it is cultural, and cities can’t change much of that, but there are things at the margins they can change – things that build a sense of distinctiveness and civic pride.

Here are three: Trademark institutions, trademark spaces, and trademark events. The easiest example of a trademark institution is a sports team, which by its nature builds loyalty to a place. But there are other examples, from museums and zoos to quirky traditions like the Peabody Hotel duck march in Memphis. (Here in Atlanta, I think of Chastain Park, home to outdoor concerts and picnics, as one of the city’s trademark institutions.) The keys are distinctiveness and authenticity. The reasons the Red Sox and Fenway Park are so beloved in Boston are because its fans can’t imagine the team in any other city and can’t imagine the team playing in any other ball park.

Trademark spaces work in a similar way: Central Park in New York, Bayshore Boulevard in Tampa, the National Mall in Washington, D.C. As with institutions, it’s important that trademark spaces reflect the character of the place. And then there are trademark events, which do double duty by building connectedness and pride in place. Yet again, distinctiveness is important. Boston doesn’t just have a marathon, it has the marathon – the first annual marathon staged anywhere in the world, as any Bostonian will tell you. Can’t be historic? Then be quirky. Chicago set off an urban craze a few years back by putting painted cow statues all over its downtown, which told residents that theirs was a city with a sense of humor. Over time, events can become so central to a city’s identity that it’s hard to separate the two.  Quick, what do you think of when you think of New Orleans? In all likelihood . . . Mardi Gras.

Point is, all of these quality of life assets build a sense of pride and belonging among citizens. (And, sometimes, a little tourism as well.) The aim is to give citizens a reason for staying, a tangible place or experience they would miss if they were to leave.

Personal growth: The third thing quality of life does is provide opportunities for personal growth and development. These could be anything from community theaters that allow people to try their hand at acting and directing to evening schools that teach art, floral design, foreign languages, cooking, great literature, and so on. These things may not be your cup of tea, but they are the passions – or, at least, the passing interests – of millions, and the communities that satisfy these needs are likeliest to hold on to their people.

Of these personal-growth institutions, I find community theaters the most interesting. According to a trade association, there are 7,000 non-professional theaters in America, staffed by 1.5 million volunteers, offering 46,000 performances a year to audiences totaling 86 million people. That’s a lot of culture and entertainment, but the real value isn’t delivered to the audience; it’s delivered to the people on stage. They’re the ones who are changed by the experience, and once changed, they’re the ones who will most likely be anchored to the community.

When you look at quality of life this way – as a way of binding people to communities through connections, identity, and personal growth – it becomes not something that’s nice to have during good times, but necessary to have at all times, even the hard ones. This is something suburban communities need to learn in a hurry. Everywhere, the suburbs are changing rapidly. Among other things, they are becoming much more ethnically diverse. Diversity is a good thing, but the reaction to diversity, particularly if it’s sudden, can be bad. As newcomers move in, some old-timers leave out of fear. We won’t miss some of these people, but wholesale flight – where families move out of fear that property values will plunge – isn’t good for communities.

We can’t stop people from leaving, but we can make them think twice about what they’re giving up, the connections with neighbors, the city’s institutions and experiences, the opportunities for learning and growth. Quality of life gives people these second thoughts. It slows them from making rash and fearful decisions. It acts like glue. And, in the end, every successful community is a sticky one.