Glamwire

As the struggles of the U.S. economy worsen, retailers and fashion brands — with California-based companies such as American Apparel helping to lead the way — are focused more than ever on the Millennials.

The poster girl for the group is Miley Cyrus, the 15-year-old star of the Disney Channel's hit series "Hannah Montana." The character she portrays has spawned an empire estimated to reach $1 billion this year through sales of everything from $6 shampoo to $29.50 jeans embellished with antique copper studs.

Females between the ages of 13 and 24 spent $33.7 billion on clothing in the 12 months through April, according to The NPD Group, a Port Washington, N.Y.-based market research firm. That compares with $16.9 billion purchased by 25- to 34-year-old women, including some older members of the Millennials, and $29.8 billion by Baby Boomers between the ages of 45 and 64.

The standards for defining this demographic vary. Different analysts describe Millennials as people born between 1979 and 1999, 1980 and 2000 or 1980 to 1995, but research firms such as Intelligence Group narrow the age range to between 14 and 29 so that they can accurately gauge the consumers' defining characteristics.

As the Millennials, sometimes dubbed Gen-Y, flex their purchasing muscle, companies are changing time-tested ways of manufacturing and marketing clothing.

"This is the generation that is rethinking everything," said Debra Stevenson, who tracks fashion and retail at her consulting firm Skyline Studios in Los Angeles. "Fast-moving trends are key because they are changing their minds quickly about things. They have a voracious interest in discovery and newness. Tried and true is not the way." Fast-fashion firms like Forever 21, Hennes & Mauritz and Zara get it. But more conventional merchants and brands, including Hot Topic and Old Navy, appeared to be slower to absorb the message.