Consumers spent $1.028-billion online during Cyber Monday, up 16 percent from a year ago, and first time such spending surpassed the billion-dollar level.

It was also the busiest online shopping day ever.

comScore (NASDAQ:SCOR), an online marketing research company, also reported that retail e-commerce spending for the first 29 days of the November - December 2010 holiday season, $13.55 billion has been spent online, a 13-percent increase versus the corresponding days last year.

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 also noted that the 16 percent surge in Cyber Monday buying was driven primarily by an increase in average spending per buyer (up 12 percent) while the number of buyers on Cyber Monday grew by 4 percent to 9 million.

The average spending per transaction grew 10 percent to $60.05, while the total number of transactions increased 6 percent to 17.1 million.

comScore added that almost half (48.9 percent) of the money spent online in the U.S. originated from work computers, representing a decline of 3.8 percentage points from last year. Buying from home comprised the majority of the remaining share (45.4 percent) while buying at U.S. Web sites from international locations accounted for 5.8 percent of sales.

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, added Fulgoni.

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.