NEW YORK — As expected, consumer caution stemming from an ongoing surge in COVID-19 cases combined with early promotions by retailers resulted in dramatically lower foot traffic and higher online sales during the Thanksgiving weekend.

According to the annual survey conducted by Prosper Insights & Analytics for the National Retail Federation (NRF), the number of shoppers in stores plummeted 55% year over year on Thanksgiving, and declined 37% on Black Friday. At the same time, the survey found that the number of Black Friday online shoppers rose 8% and exceeded 100 million for the first time. For the entire weekend, the number of online-only shoppers grew by 44% to 95.7 million.

The NRF survey estimates that 186.4 million consumers shopped in-store and online from Thanksgiving through Cyber Monday (sometimes referred to as Cyber 5), down slightly from 189.6 million last year.

The spiraling numbers of new COVID-19 cases and deaths and the resulting warnings issued by the Centers for Disease Control and Prevention to avoid large gatherings clearly contributed to the sparse in-store foot traffic. In addition, a number of retailers, including Walmart, decided to close their stores on Thanksgiving.

According to Numerator, a data and tech company serving market researchers, e-commerce’s share of the weekend’s sales vaulted to 38% from 24% in 2019, as brick-and-mortar stores’ share fell to 62% from 76%. Not surprisingly, Amazon.com emerged as the big winner, garnering 19% of total expenditures, up from 11.7% last year.

Despite the massive shift of business from brick-and-mortar stores to e-commerce, the increases in online sales for the five-day weekend fell well short of some projections. American consumers spent a record $34.36 billion online, a 20.6% increase over last year’s $28.49 billion, according to data from Adobe Analytics, which analyzed more than 1 trillion visits to retailer websites. While the increase improved over 2019’s 17.7% rise, it badly trailed Adobe’s own prediction of 38.3% and Digital Commerce 360’s forecast of a 34.9% increase.

On Cyber Monday, now typically the biggest shopping day of the year for e-commerce, Adobe Analytics calculated that consumers spent a record $10.8 billion, representing a 15.1% increase that was far below its own projection of 35.3% and about half of Digital Commerce 360’s forecast of 29.8%. The increase also failed to match the 19.7% rise achieved in 2019.

A major factor behind the unexpectedly subdued growth was the strategy of some major retailers to stretch out the shopping event with specials throughout November and even earlier in some cases. Target Corp., for example, offered deals throughout November under the slogan Black Friday Now.

“Rather than concentrating holiday deals around Thanksgiving and Black Friday, we’ve spread our Black Friday offers throughout the entire month of November, with weekly promotions spread across different categories throughout the month,” explained Brian Cornell, chairman and chief executive officer, during a conference call.

Similarly, Walmart spread out its Black Friday specials over three events dubbed Black Friday Deals for Days. The deals kicked off online at Walmart.com on November 4, 11 and 25, and appeared in stores on November 7, 14 and 27. The primary emphasis was on such categories as electronics, toys and home.

The Numerator data also revealed demographic trends in the weekend’s spending patterns. Millennials, not surprisingly, led in online purchasing, devoting 47% of their spending to e-commerce. Gen X shoppers, however, made the largest shift to online, increasing the e-commerce share of their spending to 41% from 31.2%.

Amazon.com won the highest share of spending from each generational cohort except the Greatest Generation, where it was edged out by Walmart. Walmart also had the largest share of expenditures by low-income shoppers (annual income of $40,000 or less), while Amazon claimed the largest share of high-income ($80,000 or more) shoppers’ spend at 21.9%.