But this year, major chains such as Target ushered customers in on Thanksgiving itself, turning the country's busiest shopping day of the year into a two-day affair.
Despite an outcry from some employees, both stores and shoppers seemed to like it...some people went straight from the dinner table to the stores.
"I ate my turkey dinner and came right here," said Rasheed Ali, a college student in New York City who bought a TV for 349 dollars (£218) and a sewing machine for 50 dollars (£31) when Target opened at 9pm. "Then I'm going home and eating more."
This new approach could become a holiday tradition. "This is going to be a new normal of how we shop," said Jackie Fernandez, a retail expert at consulting firm Deloitte.
It will not be clear for a few days how many shoppers took advantage of the Thanksgiving hours. But about 17% of people said earlier this month that they planned to shop at stores that opened on Thanksgiving, according to an International Council of Shopping Centres- Goldman Sachs survey of 1,000 consumers.
Meanwhile, 33% intended to shop on Black Friday, down one percentage point from last year. Overall, it is estimated that sales on Black Friday - named so because it is the day that stores traditionally move into making a profit for the year - will be up 3.8% to 11.4 billion dollars (£7.1bn) this year, according to technology company ShopperTrak. It did not forecast sales from Thanksgiving Day.
The shift began in earnest a few years ago, when stores realised that sales alone were not enough to lure shoppers, especially with Americans becoming more comfortable buying things online.
Opening on Thanksgiving was risky, with some employees and shoppers saying it was almost sacrilegious. But many stores evidently felt they needed an edge, especially this season, when many Americans are worried about high unemployment and wondering whether Congress will be able to make a deal to avoid tax increases and deep spending cuts - called the "fiscal cliff" - in January.
Overall, the National Retail Federation estimates that sales in November and December will rise 4.1% this year to 586.1 billion dollars (£366.3 billion), below last year's 5.6%. "Every retailer wants to beat everyone else," said Britt Beemer, chairman of America's Research Group, a firm based in Charleston, South Carolina. "Shoppers love it."