A worker died and at least three people were injured on Friday after being trampled by a crowd of shoppers at a Wal-Mart in the New York suburbs.
Shoppers turned out in force throughout the United States for early holiday sales.
Most stores offer major discounts the day after the Thanksgiving holiday, in what is seen as the start of the pre-Christmas shopping period, which brings in up to 40% of annual sales.
Experts predict this could be the worst holiday shopping season since the early 1990s.
Wal-Mart, Macy's, Kohl's and Best Buy opened their doors at 4am (EST), offering steep discounts to scores of shoppers who waited in line.
Some chains opened during the holiday on Thursday to capture early business.
Many started offering steep discounts on everything from clothes to electronics weeks in advance of Thanksgiving.
Sales of clothing and big-ticket luxury items have been hit particularly hard in recent months.
The NPD Group said early store traffic appeared about 25% lighter than a year ago. Chief retail analyst Marshal Cohen said people seemed to be more selective about the shops they visited and were not staying inside stores as long.
Retail sales in October recorded their biggest monthly decline since 1992. Standard & Poor's retail index is down 35% to date this year.