US holiday ecommerce sales will expand at a 15.3% clip this year, according to eMarketer's new forecast. 

As strong as that projected growth is, it's short of 2017 levels, when retail ecommerce sales soared 17.8% in November and December. 

Overall, eMarketer expects total retail sales in the US to rise 3.8% during this year's holiday season, a slower pace than last year's 5.5% gain.

"Consumer confidence in the US is high," said eMarketer's Yory Wurmser.  "With low unemployment and rising wages, the immediate outlook for consumer spending remains solid.

The picture is not uniformly bright, he warned, noting that foot traffic continues to slump. For instance, RetailNext reported that foot traffic in US retail stores slipped by 7.7% in November and by 7.5% in December.

"Still, the fact that total retail sales still grew at a healthy rate indicates that an increasing number of retailers are successfully managing the transition from primarily brick-and-mortar to omnichannel," Wormser said.

Subscribers to eMarketer's premium platform, PRO, can read the full report here. Nonsubscribers can learn more here.