E-commerce on desktop computers from November and December, excluding travel, totaled $53.3 billion, a few hundred million dollars more than expected and far greater than the $46.5 billion shoppers spent last year.

With the addition of sales via mobile devices, year-over-year growth could be as high as 17%, according to Internet Retailer, which tracks the e-commerce market.

“The 2014 online holiday shopping season was very strong overall, as spending slightly exceeded our fairly optimistic forecast heading into the season,” said comScore chairman Gian Fulgoni in a statement.

Fulgoni cited lower oil prices as one reason for the increased spending because shoppers had more money in their pockets. An improving job market and increasingly positive consumer sentiment also contributed, he said.

Cyber Monday, the Monday following Thanksgiving, ended up as the busiest day of the holiday season with online shoppers spending $2 billion, according to Comscore. It is a day when online retailers try to make a splash by offering discounts to entice more business. Despite the price cutting, Cyber Monday has often lagged behind other days closer Christmas in terms of sales. This year, however, the gimmick appears to have worked, proving some analysts wrong who had said that the day is becoming less important because of retailers increasingly discounting merchandise throughout the holidays.

The day after Cyber Monday, Dec. 2, was the second-highest day for online shopping with sales of $1.79 billion. Dec. 8, the following Monday, was third with $1.61 billion spent.

“Despite a shortened holiday calendar between Thanksgiving and Christmas and erroneous reports of flagging holiday sales, the American consumer proved resilient and flexed their spending muscle online this year,” Fulgoni said.