Online shoppers in the United States will spend $54.47 billion this holiday season, up 16.8% from $46.63 billion last year, according to a new projection from eMarketer. The market research defines the holiday season as November and December; the e-commerce estimates do not include travel purchases.

This holiday season will mark the fourth consecutive year of e-commerce spending growth. Online consumers in November-December 2008, decreased their spending by 8.2% , eMarketer says, a period when the crisis in the financial industry was turning into a deep recession, Last year, online holiday spending increased 16.5% compared with 2010.

EMarketer says online holiday spending this holiday season will account for 24.3% of all U.S. retail spending during the period. “Consumers will turn to the Internet to stay within their budgets, locate hard-to-find gifts and avoid crowded stores,” reads the report, “Online Holiday Shopping Forecasts and Trends.”

Other e-commerce experts echoed the view that online holiday sales should prove robust this year. ”The overall growth we’re expecting should be in line with 2011 or potentially slightly better,” says Eric Best, CEO of Mercent Corp., which helps retailers sell online through marketplaces and comparison shopping engines. “When you look at the first half of 2012, we’ve been seeing strong performance overall due to very strong results from a lot of the channel partners that we enable for our retail customers, including Amazon and eBay.”

In its report, eMarketer also highlighted the following trends for this year’s holiday shopping season:

• Consumers will have more daily deals and limited-time sales to choose from. In 2011, about one of five shoppers bought a holiday gift via a daily deal site, eMarketer says, citing data from web measurement firm comScore Inc.

• Consumers will become ever more comfortable with researching online and then buying inside bricks-and-mortar stores. “Cross-channel shopping is not new, but it will become more routine for shoppers who have developed greater versatility at combining the Internet, stores, smartphones and tablets to achieve their gift-buying objectives,” the eMarketer report says.