Excerpted from The Social Life of Small Urban Spaces, by William H. Whyte

If you want to seed a place with activity, put out food. Food attracts people who attract more people. In New York, at every plaza or set of steps with a lively social life, you will almost invariably find a food vendor at the corner and a knot of people around him - eating, schmoozing, or just standing. Vendors are the caterers of a city's outdoor life. They flourish because they're servicing a demand not being met by the regular commercial establishment. Plazas are particularly parasitic in this respect. Hardly a one has been constructed that did not involve the demolition of luncheonettes and restaurants. The vendor thus fills a void, and this can become quite clear when he is shooed away. A lot of the life of the space goes with him.

Vendors have a good nose for spaces that work. They have to. They are constantly testing the market, and if business picks up in one spot, there will soon be a cluster of vendors there. This will draw more people, and yet more vendors, and sometimes so many converge that pedestrian traffic slows to a crawl. In front of Rockefeller Plaza during the Christmas holidays, we've counted some 15 vendors in a 40-foot stretch (most of them selling hot pretzels).

Food attracts people who attract more people. We had an excellent opportunity to observe this shill effect through some semicontrolled experiments at a new plaza. At first there was no food. A moderate number of people used the place. At our suggestion, the management put in a food cart. It was an immediate success (a flower cart was not). More people came. A pushcart vendor set up shop on the sidewalk, then another. Business continued to pick up, for all three vendors. Next, the management got the restaurant in the building to open a small outdoor café. More people came and yet more - over and above the number who used the café.

The optical leverage in these things is tremendous. For basic props, nothing is more needed than a pushcart, and several stacks of folding chairs and tables. Set up a kiosk or a pushcart, spread the chairs out, put up the colored umbrellas, and the customers and the visual effect can be stunning. Instead of distributing the facilities over a large space, group the tables and chairs close together. As a consequence, people will be compressed into meeting one another easily; waiting in line or weaving their way through the tables. Very quickly, the space can became a great social interchange for pedestrians.