Online shoppers in the United States spent nearly $37.2 billion during the 2011 holiday season, up 15% from the approximately $32.4 billion spent in 2010, comScore says. The web measurement firm accounted for spending between Nov. 1 and Dec. 31.

The 2011 holiday season marked the best holiday shopping year ever for e-commerce, comScore says. Consumers on 10 days during the 2011 holiday season spent more than $1 billion, with Cyber Monday—that is, the marketing name for the first workday after Thanksgiving—bringing in $1.25 billion for e-retail.  That was the heaviest online shopping day in history.

The growth for e-commerce has outpaced the growth for bricks-and-mortar stores during the holiday season. For the week ending Dec. 31, retail sales at bricks-and-mortar stores increased by 5.3% over last year, according to the latest estimate from the International Council of Shopping Centers and Goldman Sachs Weekly Chain Store Sales Index.

“With bricks-and-mortar holiday retail estimated to have grown about 4% this year, it’s clear that e-commerce continues to gain market share from traditional retail due to the attractiveness of the Internet’s convenience and lower prices,” says comScore chairman Gian Fulgoni. “Consumers were especially attracted to the deals and discounts available through digital channels,  particularly free shipping, which occurred on well over half of transactions this season.”

According to comScore, here are the most lucrative days of the 2011 holiday shopping season:

• Monday, Nov. 28 (Cyber Monday), $1.251 billion

• Monday, Dec. 5, $1.178 billion

• Monday, Dec. 12 (Green Monday), $1.133 billion

• Tuesday, Nov. 29, $1.116 billion

• Tuesday, Dec. 6, $1.107 billion

•Friday, Dec. 16 (Free Shipping Day), $1.072 billion

• Tuesday, Dec. 13 $1.064 billion

• Wednesday, Nov. 30, $1.025 billion

• Thursday, Dec. 8, $1.024 billion

• Thursday, Dec. 15, $1.018 billion

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