Nearly half of the U.S. adult population has made a purchase online, taking e-commerce from a dot-com novelty to the mainstream, according to a survey by Nielsen//NetRatings and Harris Interactive.

The eCommercePulse online survey of 39,000 Web users found that 100.2 million U.S. adults, or 48.2 percent of the U.S. adult population age 18 and over, have purchased online. More than 81.2 percent of all adults with Web access have made a purchase online since they started using the Internet.

"Online shopping is not trivial when more than 80 percent of all Web surfers and nearly one out of every two Americans are involved - e-commerce has gone mainstream," said Sean Kaldor, vice president of eCommerce at NetRatings.

More than $3.5 billion was spent online in March 2001, a 35.6 percent increase from $2.6 billion in April 2000. Two product categories accounted for more than half of this growth: online travel spiked 58.5 percent to more than $1 billion dollars in March 2001, while clothing and apparel jumped 122.3 percent to $368 million.

"Despite challenges in the U.S. economy, online spending is holding strong, even gaining four percentage points from February to March 2001," Kaldor said.

Amazon led the e-commerce market in March, garnering 15.1 percent of all online buyers. eBay followed closely with 14.5 percent of all online purchasers, while BMG Entertainment's share was 4.3 percent. Barnes & Noble (3.8 percent) and Columbia House (3.7 percent) rounded out the top five rankings.

"While Amazon commands much of the attention in e-tailing, eBay attracts nearly as many customers," Kaldor said. "In fact, adding eBay's numbers to its subsidiary Half.com shows it has more customers online than any other merchant."

Despite strong showings by online outlets such as Amazon and eBay, e-commerce is fast becoming the domain of traditional retailers, which are often best positioned to handle the economics of online retailing and capture growing consumer demand. The report "The Next Chapter in Business-to-Consumer E-Commerce: Advantage Incumbent" by the Boston Consulting Group (BCG), found that bricks-and-mortar retailers have a golden opportunity to use their inherent advantages to expand their customer share dramatically.

"Online retailing is entering a new phase in its evolution," says Michael Silverstein, senior vice president and global leader of BCG's Consumer practice. "What was once an industry characterized by entrepreneurial dot-coms, targeting the discretionary spending of the Internet-savvy consumer, is fast becoming the domain of traditional retailers, selling both necessities and discretionary items to the broader population."

BCG's report also predicts the long-term prospects for online retailing are strong, as demand for goods and services online will continue to grow as consumers become more accustomed to multichannel shopping. Sales in the nine leading online categories have the potential to grow from $34 billion in 2000 to $168 billion by 2005. Most of the growth will take place in the leisure travel, grocery and clothing categories.

Top E-Tailers of March 2001 Ranked by Share of Purchasers
Rank	Site	Unique Audience (000)	Purchaser Share (%)
1.	Amazon.com	22,751	15.1
2.	eBay*	18,987	14.5
3.	BMG.com	4,762	4.3
4.	Barnes & Noble	5,948	3.8
5.	ColumbiaHouse.com	2,723	3.7
6.	Half.com	4,939	3.1
7.	JCPenney.com	3,339	3.0
8.	Travelocity	7,966	2.5
9.	CDNow.com	5,295	2.2
10.	Southwest.com	3,954	2.0
* Does not include Half.com subsidiary Source: Nielsen//NetRatings & Harris Interactive