Up to 30 million people will take to the streets and parks, with no one calling the cops. Indeed, local police departments help organize this evening of block parties, neighborhood festivals and music performances. The idea is that when people step out of their homes to meet the neighbors, communities are safer. People who know one another are more likely to work together to prevent crime in their community.

For most people, neighborhoods are a form of the commons that is most familiar. Nearly every one of us lives in one, and they are important to our lives whether we realize it or not. If your home is burglarized while you’re away, it’s your neighbor who calls the police. Even more likely, your neighbor’s presence strolling down the sidewalk or keeping on her porch light discourages hoods from breaking in at all.

That’s why police want to mobilize the power of the commons for fight crime. Spending many years out on the streets, they have come to understand that government and the private sector can only do so much to assure public safety. A lot depends on people themselves, working together in informal but powerful ways to protect their community from violence, theft and vandalism.

But crime is only one of many serious problems that can be effectively addressed at the level of the neighborhood commons. So can issues related to the environment, economic decline, and social alienation.

All of us are more likely to pitch in on causes that affect our own backyard. Destruction of the rainforest upsets us, but a threat to beloved trees a few blocks away will get us off the sofa to circulate petitions, organize protests and negotiate with the folks wielding chainsaws.

And when we can see the direct effects of our actions, we are much more likely to stay involved and broaden our focus from local to global issues. Saving the trees in our neighborhood can inspire us to save the rainforest, too.

The notion of the neighborhood as an important social institution might seem old-fashioned (as is the idea of the commons itself) to some, like nostalgic memories of the corner soda fountain. Yet it’s actually as up-to-date as an internet café, where you find people communicating with New Zealand and Morocco at their laptops but also striking up conversations with someone at the next table.

The mark of the 21st century person is to step out into the world on one foot but have the other squarely planted in his or her community. Even as our intellectual and economic horizons expand, the local community is still where we lead our lives, where our toes touch the ground, where everybody knows our name. Being rooted in the neighborhood of your choice (which may be far from the neighborhood where you grew up) offers not just comfort but a prime opportunity to make a difference in the world.

When you add up the people all over the world who are working to change things in their own neighborhoods—the results are impressive:

• In Porto Alegre, Brazil, (population 1.3 million), local officials enlist the wisdom of neighborhood residents in figuring out how to best apportion their tax money. Citizens gather in neighborhood assemblies to decide what’s needed in their part of town, and then elect representatives to advise the city council on budget priorities. This “participatory budget” has been credited with lowering unemployment, improving sanitary conditions and revitalizing Porto Alegre’s poor neighborhoods. More than 1,200 cities across the world have now adopted the idea.
• A group of frustrated neighbors in Delft, Netherlands, finally took action about autos speeding down their street. They dragged old couches and tables into the middle of the road, strategically arranging them so that motorists could still pass—but only if they drove slowly. The police eventually arrived and had to admit that this scheme, although clearly illegal, was a good idea. Soon the city was installing its own devices to slow traffic, and the idea of traffic calming was born—an innovative solution that used across the globe to make streets safer.

• Grandmothers at the Yesler Terrace public housing project in Seattle drove drug dealers from their community by camping out in lawn chairs at street corners notorious for crack traffic. They simply sat there knitting, and the dealers soon cleared out, proving that frail old grannies willing to speak up for their neighborhood can sometimes accomplish more than cops in squad cars.

Neighborhood activism is often cast as a narrow, even selfish pursuit. People are starving in Africa, critics charge, and you’re obsessed with starting a farmer’s market! But that ignores two of our chief assets for social change in the 21st century.

1. Thanks to our amazing global communications networks no good idea stays local for long.

2. And when a citizens group or social movement is infused with the spirit of the commons, they naturally make the connection to similar efforts elsewhere.

There’s no better time in history, as the old saying goes, to think locally and act globally.

This article is based upon research for The Great Neighborhood Book, a guidebook of practical ideas and success stories from around the world created with Project for Public Spaces

It is tempting to dismiss locally grown food as just another elite fashion, as many people surely will. But it is also true that wealthy households are often the first to validate broader market trends.

Consider it another chapter in the ongoing dance between the commons and the market. The commons lovingly advances a new ideal – in this case, the ecological virtues, social satisfactions and great taste of locally grown food. And then, after years of hippies, homesteaders and eco-evangelists beating the drum for this new ideal below the radar screen of mainstream culture, entrepreneurs suddenly get hip to what’s going on and swoop in to make money from a grassroots trend.

Photo by asmart42, via Flickr, licensed under a Creative Commons BY-NC-ND license.

Some things never change. We are at that special inflection point in the evolution of social attitudes that are mysteriously propelling the rise of a new market niche. Its customers, the aficionados of local food, even have a name – “locavores.” There are also novel sorts of new businesses.

As the Times reports, Trevor Paque has made a business in San Francisco planting vegetable gardens for affluent suburbanites who want to eat garden-grown food, but who don’t like to garden. So Trevor does the planting, weeding and harvesting. A company called FruitGuys will deliver boxes of locally grown, sustainably raised or organic fruit to people in San Francisco and Philadelphia.

Soon mega-millionaires like Bill O’Reilly and Rush Limbaugh will rail against the trendiness of local food. That’s their schtick, after all – to invent elite foils for themselves so that they can cast themselves as Main Street populists. Real Republicans only eat red meat and potatoes, it would seem.

This is just a shell game in the culture wars, however. I am convinced that local food is going to become a steady, long-term growth market. For its taste, cost and eco-friendliness, local food has already become a symbol of social virtue. People are starting to realize that it is not so good for the planet to haul meat from New Zealand, wheat from South Dakota and fruit from Caifornia. Social demand and sheer economics are starting to buoy local growers, and supermarkets are looking for new ways to call attention to their local produce. The trend lines are clear.

The spending of local money for local produce is surely a virtuous cycle for local economies. It is also likely to promote greater personal connections among people locally, stronger commitments to one’s local community, and a more stable and diverse local economy.

Two days after filing the local foods article, Kim Severson, the same Times reporter who wrote about the elite embrace of local foods, had another piece about the upcoming an upcoming festival called Slow Food Nation. The event, to be held in downtown San Francisco over Labor Day weekend, will feature pavilions devoted to foods like pickles, coffee and salami. A quarter-acre patch of the lawn in front of City Hall has been ripped up to grow a garden.

Slow Food Nation is an ambitious attempt by Slow Food USA, the American spinoff of the Italy-born Slow Food movement, to establish itself as a recognized political and cultural force. Organizers hope the festival will be, in the words of Severson, “the Woodstock of food, a profound event where a broad band of people will see that delicious, sustainably produced food can be a prism for social, ecological and political change.”

I am sure that certain elements of the Slow Food world will behave like effete connoisseurs and fawn over the local argula and goat cheese. But really, is that so bad? Why shouldn’t people start to express their affection and appreciation for local food? If cultural snobs and the wealthy can embrace a populist trend without coopting it – validating it with their presence and boosting it with their dollars – I say, bring ‘em on. Let everyone celebrate the taste of local food – and then move on to the political and economic realities that sustain it.

If local food is going to be a victim of identity politics, let it be a politics of localism: “We all live here together, so let’s find the way to support the farmers who are our neighbors.”