US sales from internet retailers rose 19% between 1 November and 27 December compared with the same period of 2006, a report estimated.
comScore said warm November weather depressed online sales
The online information group comScore said that online spending excluding travel and auctions came in at almost $28bn (£14bn).
It said that the growth is impressive given the current economic problems.
But the 19% growth was well below last year's rate of 26%, which the firm blamed on warm weather in November.
"Warm weather during the early part of November took its toll on online retail sales, and played a role in holding down the growth in spending over the entire holiday season," said comScore chairman Gian Fulgoni.
"However, if we look at the period between Thanksgiving and Christmas, we see online spending growing at a healthier 21% rate, which I think is encouraging given the economic challenges facing consumers this year as a result of higher gas prices, lower home values and a jittery stock market."
Thanksgiving is celebrated in the US on the fourth Thursday in November, which this year was 22 November.