n. A group of city dwellers who have formed a bond through a common interest, such as work or a social or recreational activity.
2001
Once I identified this in my own life, I began to see tribes everywhere I looked: a house of ex-sorority women in Philadelphia, a team of ultimate-frisbee players in Boston and groups of musicians in Austin, Tex. Cities, I've come to believe, aren't emotional wastelands where fragile individuals with arrested development mope around self-indulgently searching for true love. There are rich landscapes filled with urban tribes.
1983 (earliest)
A new look is spreading through the city's storefronts, billboards, houses and cinderblock fences — the clean wall. Many of the structures are emerging for the first time in years from the spray-paint masks of gang graffiti wars. They are the first tangible successes of a novel program to rid Los Angeles of the ubiquitous signatures of its urban tribes.
The New York Times essay by Ethan Watters cited above has caused a bit of a ripple in the media waters over the past few months, with some even claiming that Mr. Watters coined the term urban tribe. Uh, nope. Thanks for playing, though. As you can see from the earliest citation, the phrase is almost 20 years old.