Shoes...shoes...shoes...everybody likes to buy shoes

The Gap has long been known for casual jeans and T-shirts, but the ubiquitous chain hopes it will soon be known for something else: shoes.

Earlier this month , Gap Inc., the San Francisco parent company of Banana Republic and Old Navy, launched Piperlime, an online store that sells 100 brands of shoes. It's a big step for a chain that has become known for its own labels.

"There's a huge demand for shoes," said Alex Clark, a company spokesman, "and it's growing."

Shoe fans take note: Retailers are at your feet. Clothing stores from Talbots to H&M have been beefing up their footwear collections. The off-price retailer Marshalls has expanded shoe departments at 40 of its stores across New England, devoting as much as 10,000 square feet to shoes, up from an average of about 2,500. Famous Footwear has opened 90 stores nationwide this year, and teen retailer Pacific Sunwear has started a sister chain, One Thousand Steps, devoted almost entirely to shoes.

Shoes increasingly are becoming every season's must-have accessory: Between 2000 and 2005, US footwear sales rose 19 percent to about $49 billion, and they are expected to grow another 23 percent by 2010, according to Mintel Group, a Chicago market research firm. Women's clothing sales, on the other hand, rose only 2 percent between 2000 and 2005, and researchers predict growth of 9 percent by 2010.

Women alone spent $18.3 billion on fashion footwear over the past year , up from $15.6 billion two years ago , according to the NPD Group, a market research firm in Port Washington, N.Y. That amounts to roughly 884 million pairs of women's shoes, according to trade group American Apparel and Footwear Association.

Mintel suggests that the clothing industry could do a better job of reaching certain audiences, such as women over 45 and women who wear plus sizes. The shoe industry, however, has been successful in captivating its audience with a variety of styles and prices, said NPD analyst Marshal Cohen. Shoes, like handbags before them, have become the item that defines many women's individual styles.

"What's happening really is that footwear as a whole is becoming a signature item," he said.

Scott Cooper, senior vice president of marketing for retailer Famous Footwear, which has 23 stores in the Greater Boston area, attributes the fascination with footwear in part to popular culture's obsession with shoes (the legacy of TV show "Sex and the City") and also to the recent economic downturn, which for many consumers meant less money for new clothes and, in turn, more money for accessories.

Manufacturers and retailers have been quick to pick up on shoe trends, he added, offering "sports fusion" styles (think Puma or Skechers) and "world bazaar" styles such as sequined slippers. "Blue jeans are blue jeans, but how many different shoes can you wear with blue jeans?" Cooper said.

While Famous Footwear used to stock new shoes for three seasons, Cooper said, over the past four years they have begun stocking for about six seasons, including Easter. And within each season, they regularly introduce new merchandise so consumers will always see something new.

"Think about how people shop for shoes," he said. "It's much more spontaneous."

But selling shoes can be tricky for retailers because it requires keeping a lot of stock on hand. Given the different sizes, styles, and widths, retailers could need up to four times more inventory of shoes than of some kinds of apparel, Cohen estimates.

"Retailers shied away from it," he said. "For me to sell one pair, I've got to have 40 pairs on the shelf."

John Shanley, senior athletic and footwear analyst for Susquehanna International Group, says women's fashion footwear is the most robust part of the shoe market, but also questions how much success apparel companies can have in what he describes as a complex and challenging industry. Shoe specialty chains such as DSW and Famous Footwear have recently been successful, he said, because many women enjoy the self-service model, and because the closure of department stores such as Filene's has allowed the specialty chains to expand.

To increase shoe sales, Hingham-based Talbots, which has sold shoes since 1947, recently began offering a higher-priced footwear collection averaging around $158 a pair, says Talbots fashion spokeswoman Betsy Thompson.

Meanwhile, Pacific Sunwear has opened nine One Thousand Steps locations, including one in Providence, which are meant to appeal to customers 18 to 30 years old. Footwear accounts for about 15 percent of Pacific Sunwear's business, and the company saw opportunity after noticing that many customers were shopping elsewhere for shoes, said Gar Jackson, the company's director of investor relations.

Some companies have sidestepped inventory issues by selling shoes on the Web. Online fashion footwear sales grew to $955 million over the past year, up from $674 million the previous year, according to NPD.

Zappos.com has sold shoes online since 1999. The Las Vegas company offers 900 brands, including luxury labels, and expects its sales to reach $600 million this year, said chief executive Tony Hsieh.

Because the company offers free shipping on returns, many customers will buy a few different sizes, Hsieh said, knowing they can try everything on at home and send back what they don't want. "We really think of it as bringing the shoe store into the customer's living room," he said.

The Gap brands have sold their own lines of shoes for years but saw the launch of Piperlime as a way to further tap the market.

The company wouldn't give out projected sales of its new site, but has said it sees its Web operations as a growth center, with e-commerce sales rising 27 percent last quarter.

One of Piperlime's first customers, Jackie Acuff, said she shops for shoes online if she can't find her size in a store. The New Yorker estimates that she has bought about six pairs -- a quarter of her total shoe purchases -- off the Internet this year.

The strong shoe market can also be attributed to shoppers like Emily Shannon. Holding up a pair of silver Manolo Blahniks at Neiman Marcus in Boston, Shannon admitted that most people would probably consider it "ridiculous" to spend $400 for a pair of shoes.

But the technical support engineer who lives in Dorchester said shoes are something she can wear for several years. After she turned 30, she said, she realized clothes didn't come with such a guarantee. "Your feet don't generally get larger," she said.

Emily Shartin can be reached at eshartin@globe.com.