Specialty rules. (Cover Sory).(stores for teens)(Statistical Data Included)

The so-called teenage wasteland has never been so fertile.

Visit your local mall, and you'll see a slew of specialty stores, established and new, catering to those who frequent it so devotedly--teens.

Pegging each store's niche is as simple as checking out the high school cafeteria, Mall stores personified are stereotypical teens--jocks, skaters, even pierced rebels smoking outside.

These narrowly focused chains, from American Eagle to Wet Seal, are quickly encroaching on territory traditionally held by more broad-based specialty shops.

As a group, young men's and juniors apparel store sales rose a whopping 24.3 percent, with units up 10 percent, in the first half of 2001--faster growth than in any channel researched--according to The NPD Group.

Meanwhile, former watershed Gap Inc.'s chains had negative comps almost every month of 2001, with December comp sales down 11 percent and overall sales falling resoundingly flat. U.S. Bancorp Piper Jaffray saw Gap Inc.'s stores drop to No. 4 from No. 1 in popularity when it surveyed about 600 students nationwide-- Abercrombie & Fitch and American Eagle were No. 1 and No. 2, respectively.

The Gap and other establishments that haven't followed this trend of differentiation have suffered. Limited Inc. is phasing out Structure, with negative 6 percent December comps, changing stores to Express Men's. The merchandise will move to a more specialized high-fashion look, mirroring Express.

Here's a "yearbook roster" of some specialty standouts:

THE JOCKS: Playing to the junior varsity set, …