According to preliminary data, Black Friday online sales rose 19.7 percent.

Black Friday shoppers at the Jersey Shore Premium Outlet in Tinton Falls (Annette Petriccione, Townsquare Media NJ)

Store sales numbers won't be available until Saturday. But IBM Benchmark, which tracks e-commerce for 800 retailers, said online sales on Thanksgiving were up 19.7 percent from last year.

Retailers know they drew a lot of people for the opening of the holiday shopping season, which pushed across the Thanksgiving Day boundary in a bigger way this year. More than a dozen major U.S. retailers stayed open for 24 hours or more on Thanksgiving through the day after known as Black Friday.

As always, the challenge now is to keep the momentum going.

Black Friday, the official start of the shopping season between Thanksgiving and Christmas, originally was named that because it was when retailers turned a profit, or moved out of the red and into the black. Retailers opened early and offered deep discounts.

The earlier openings have met with some resistance, including from workers' rights groups.

(Copyright 2013 The Associated Press. All Rights Reserved)