The number of weekend shoppers rose to 141 million, up 2 million from last year's 139 million, a survey released by the National Retail Federation said.
Shoppers spent an average of $407.02 between Thursday and Sunday, down 4 percent from last year's $423.55, the retail-trade group said.
Overall sales slipped 2.9 percent from 2012 to an estimated $57.4 billion.
"With limited budgets this year, holiday shoppers will continue to make very thoughtful decisions about when and where they shop the remainder of the season," said Pam Goodfellow, consumer insights director of Prosper Insights & Analytics, which conducted the survey for the retail-grade group.
Increasing numbers of shoppers decided to shop online, the survey indicated.
Of the total number of shoppers, the 42 percent, or 59 million people, who said they shopped online spent an average $177.67 during the weekend, or about 44 percent of their total weekend spending, the survey indicated. That was up from 41 percent last year and 23 percent in 2006.
Cyber Monday sales could be the biggest on record, approaching $2 billion, up about $530 million from last Cyber Monday's $1.47 billion, the comScore Internet analytics firm forecast.
Cyber Monday 2012 represented the heaviest online-spending day in history.
The National Retail Federation survey of 4,464 consumers has an error margin of 1.5 percentage points.