ComScore, an analytics firm whose data is closely watched by Wall Street, said U.S. online sales rose a total of 17.3 percent on Thanksgiving and Black Friday, the unofficial kick-off to the holiday spending season.
Meanwhile, the National Retail Federation estimated on Sunday that retail sales over the full Thanksgiving weekend will reach $57.4 billion, with the average shopper spending $407.02, down from $423.55, because of lower prices.
The NRF released a survey saying: More than 141 million unique shoppers have already or will have shopped by the end of the big Thanksgiving weekend, up from 139 million over the same time frame last year.
For those who shopped multiple times over the weekend, the survey found more than 248 million waited in line, took advantage of big discounts offered throughout the mall and shopped on retailers websites, up from 247 million shoppers last year.
According to the NR survey conducted by Prosper Insights & Analytics over the weekend, traffic on Thanksgiving Day itself grew 27 percent as nearly 45 million shoppers, or 31.8 percent of holiday shoppers, took advantage of special "turkey day" savings offers, up from 35 million in 2012.
Black Friday was the biggest day: more than 92 million people shopped (65.2 percent) for apparel, electronics and more, up from nearly 89 million last year.
Low prices helped keep Americans' budgets in check this weekend: on average,shoppers spent $407.02 from Thursday through Sunday (planned), down from$423.55 last year. Total spending is estimated to reach $57.4 billion.
"Cold weather, unique promotions and unbeatable prices put millions of Americans in the mood to shop for holiday gifts this weekend," said NRF's CEO and president, Matthew Shay.
Thanksgiving weekend deals are especially enticing to young people. More than three-quarters (76.2 percent) of 18 – 34 year-olds shopped or planned to shop over the holiday weekend – higher than any other age group – with Black Friday being the most popular day (70.9 percent).
More from Survey: Shoppers visited stores earlier
Eager to kick off the holiday shopping season, one-quarter (25.4 percent) holiday shoppers say they were at stores by 8 p.m. on Thanksgiving night; nearly four in 10 (37.3 percent) were at stores by midnight, up from 28.0 percent last year. Early hours aren't for everyone however; more than one-third didn't arrive at stores until 10 a.m. or later.
(Read more: J.C. Penney's $1.97 pants could spoil Christmas)
The weekend shopping excitement wasn't limited to stores; consumers also spent more of their holiday budgets online. According to the survey, four in 10 indicated they shopped online over the weekend, or approximately 59 million shoppers.
Clothes,electronics, and books, DVDs and video games were among the popular items purchased over the weekend. Nearly six in 10 (57.5 percent bought clothing and clothing accessories, 37.7 percent bought electronics, 34.5 percent bought toys, and 36.1 percent bought books, CDs, DVDs and video games. Additionally,29.6 percent bought gift cards and 16.9 percent purchased jewelry items.
More than 76 million (54.2 percent shoppers visited their favorite department store over the weekend, and nearly 55 million (38.9 percent) visited discount stores.Additionally, 32.2 percent (45 million) shopped at electronics stores and 28.7 percent, or 40 million, went to clothing or accessories stores for gifts.
Additionally,slightly fewer people (76.4 percent vs. 79.6 percent) this year said they took advantage of retailers' online and in-store promotions to buy non-gift items.
According to the survey, almost half (49.2 percent ) of holiday shoppers over the weekend sought out information about promotions and sales via advertising circulars, and one-third conducted online searches to find the best deals.
Additionally, 36.8 percent made sure to keep track of emails from retailers, 16.4 percent reviewed retail companies' Facebook accounts for information, and 12.2 percent browsed stores to find bargains and sales.
(Read more: Game on for a retooled Best Buy)
—By Reuters. CNBC contributed to this report.