• by Sarah Mahoney  @mahoney_sarah, March 13, 2013

Fueled by mobile and multichannel offerings, America’s enthusiasm for online shopping shows little sign of slowing down, according to Forrester’s just-released forecast for the year ahead. E-commerce sales in the U.S. are likely to climb 13% to total $262 billion in 2013, or 8% of total retail sales. And that number is expected to reach $370 billion by 2017, or 10% of total sales, predicts analyst Sucharita Mulpuru. That reflects a 10% compound annual growth rate.

“This growth will be abetted by traditional stores’ investments in web businesses to support a multichannel strategy, the blistering pace of mobile device adoption, and the fact that consumers are more comfortable with purchasing online,” she writes.

In part, she says, large brick-and-mortar stores such as Macy’s and Nordstrom are fueling the growth. “For years, large retailers have seen the value in cross-channel investments like in-store pickup, endless-aisle capabilities, and cross-channel inventory visibility.” While she says few have executed them well, those that have say that up to half of web sales stem from efforts like “endless-aisle initiatives (in which store associates “save a sale” by ordering an out-of-stock item for a shopper through a web-enabled point-of-sale system).”

Also fueling the growth is post-supper shopping, with millions of consumers lounging on couches, using tablets and smartphones to browse and buy during the evening hours. Rapid smartphone adoption is part of that, but tablets are also transforming e-commerce. “Virtually all retailers report that traffic to their sites from tablets spikes during evening prime-time hours, when consumers are in a leisure state of mind,” the report says. “This also suggests incremental web sessions and conversions, because web retail traditionally spikes not in the evening, but during business hours.”

Online loyalty programs are also adding to the steady growth.

The report also zeros in on e-commerce as a booming employment opportunity, currently employing 400,000, and expected to reach 500,000 by 2017.