How’d things get this way?
Not every category of product or service, of course, has its own neighborhood. There’s no fast-food district. There’s no concentrated nabe for sneakers or spectacles or Starbucks or Staples. So what’s different about boutiques or guitars?

Economists have devoted a lot of attention to the question of retail site choice; “location theory” or “geographical economics” is a recognized specialty within the field (Princeton’s Paul Krugman, whom many consider the most important economics writer since John Kenneth Galbraith, pioneered in it). Rental costs, transportation, demographics, and a kazillion other variables are involved – the math gets formidable, and this column is no place for math – but one of the critical principles has to do with differentiation in the goods themselves.
In a field where the products are pretty similar, and shoppers are mainly comparing prices, there’s rarely an advantage in clustering. It’s more likely to be a disadvantage, because close proximity would mean heated price competition: great for the consumer, rough on the vendors, and the vendors make the decisions on this. All other factors being equal, vendors of basically similar goods will usually distance themselves from each other. If all the movies playing in a city are the same dozen-or-so Hollywood blockbusters (which is often the case in small or medium-sized cities), the movie theaters will be spread out. Cities don’t generally have a cinema district.

If the items are substantially different, on the other hand, and shoppers are looking for specific things rather than just a good deal on the same things, then it makes sense for vendors to be near each other. A condensed district is more convenient for customers and suppliers; it’s also conducive to communications within the field (particularly if the field involves a specific ethnicity, culture, or language – Brazilian restaurants on W. 46th Street, Korean establishments on W. 32nd, kosher delis in yesterday’s Lower East Side or today’s Williamsburg). Even within a well-defined cuisine, food differs widely from place to place, as every discerning diner knows. So do non-mainstream films and any type of live performance. There’s only one version of any given stage show, whether it’s an expensive Broadway production or a downtown black-box experimental piece. So there are theater districts.

Antiques? Broadway between 14th and about 10th. Florists? The west Twenties. Flea markets? Also the west Twenties, particularly around the corner of 26th and Sixth.

In some fields, geographic concentration is a no-brainer everywhere, not just in NYC. The lawyers are concentrated near the courthouses. The financial firms are close to the trading floors. The same goes for porn and strip joints, because public policy and police crackdowns tend to cordon off those trades into what were once called red-light districts (or, in Boston, the Combat Zone). With other commodities, transportation and perishable goods dictate a concentrated location: without the Meatpacking District in the far West Village, or downtown’s Fulton Fish Market (soon to move to Hunts Point in the Bronx), shippers and buyers would have to make too many stops, with aromatic consequences I don’t dare to contemplate.

Art? The gallery centers used to be SoHo and the EV; lately the hot nabes are Chelsea and Williamsburg and DUMBO; next year, maybe Long Island City. The art world -- with its unique needs for large cheap real estate, deep-pocketed speculators, and strollable spaces between galleries -- plays by its own rules, and it doesn’t gather a whole lot of moss. (But that’s a whole different article. More likely, several of them.)

All these specific districts have arisen and endured through confluences of economics, choices about infrastructure, immigration patterns, and the quirks of history. Underlying the whole process are the hyperdensity and hyperdiversity that define New York; there’s just so much of everything, and so much variety within categories, that concentration naturally leads to convenience.

And don’t overlook the feature that makes NYC different from every other location in the U.S.: the automobile doesn’t dominate our way of life. When most people walk or take public transportation instead of driving, everything in public space can take a unique shape. For the price of an occasional tough schlep when we need to haul something home, freedom to deviate from the homogenized landscapes dictated by King Car strikes us New Yorkers as a pretty good deal.

Writer/editor/musician Bill Millard is editor-in-chief of a new publication, The Guide to NYC’s East Village. His articles on culture, architecture, and politics have appeared in Content, Icon, and other magazines; he also plays, sings, and writes with rock band Shanghai Love Motel.