Americans jumped on deals and promotions offered online on Cyber Monday, spending $1 billion and making it the busiest online shopping day ever, according to new data.

Research firm comScore Inc. says revenue rose 16 percent from a year ago to $1.03 billion on the Monday after Thanksgiving. Since the beginning of November, online sales are up 13 percent to $13.55 billion.

“Cyber Monday reached $1.028 billion in online spending, up 16 percent versus year ago, representing the heaviest online spending day in history and the first to surpass the billion-dollar threshold,” the company said.

The improvement is welcome for retailers hoping that Americans start spending more freely. But shoppers are still holding out for bargains and spending cautiously as unemployment remains high.

The total also reflected a record-setting day for Morrisville-based ChannelAdvisor, which provides e-commerce related services. (Read LTW coverage here.)

“Cyber Monday was a historic day for e-commerce as we saw daily spending surpass $1 billion for the first time,” said comScore chairman Gian Fulgoni. “The online holiday shopping season has clearly gotten off to a very strong start, which is welcome news. At the same time, it’s important to note that some of the early strength in consumer spending is almost certainly the result of retailers’ heavier-than-normal promotional and discounting activity at this early point in the season. So, while we anticipate that there will be more billion-dollar spending days ahead as we get deeper into the season, only time will tell if overall consumer online spending remains at the elevated levels we’ve seen thus far.”

ComScore did note a change in e-commerce buying – Shopping by people at work declined to 48.9 percent from 52.9 percent while home buying climbed to 45.4 percent from 41.6 percent.

“Since its inception, e-commerce activity has been driven heavily by people making online purchases while at work, an effect that is magnified on Cyber Monday as people return to their desks after the Thanksgiving holiday weekend,” Fulgoni explained.

“While online shopping from work originally occurred to take advantage of broadband speeds that people lacked at home, it was widely believed that this would decline markedly as home broadband connectivity increased. The fact that spending from work remains so prevalent suggests other explanations. It is more likely that consumers continue to shop from work primarily because by doing so they are able to shop for holiday gifts while minimizing the risk that their children, spouses and significant others might see what Santa will bring.”

According to ShopperTrak figures, revenue at brick-and-mortar stores was flat over the weekend following Thanksgiving, but traffic rose 2.8 percent.

A clearer picture of spending will come Thursday when the nation’s retailers release revenue figures for November.

For the full comScore report, read here.

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