This year’s Black Friday looked nothing like a usual one. Crowds at suburban malls and city shopping districts were comparatively sparse. With the coronavirus touching virtually every corner of the United States, social distancing, restrictions on business activity and health concerns kept many people home.

They shopped online, however.

According to Adobe Analytics, which scans 80 percent of online transactions across the top 100 U.S. web retailers, consumers spent $9 billion on Friday. That’s a 21.6 percent increase over Black Friday in 2019 and the second-biggest number for online retailers Adobe has ever tracked. In the four days from Thanksgiving through Sunday, consumers spent $23.5 billion online, a 23 percent increase over last year, according to Adobe.

Another research firm, Facteus, which monitors millions of debit and credit card payments made in the United States, found that department stores’ in-person sales fell significantly on Friday, but that their online sales spiked. The firm found a similar pattern for electronics retailers.

And Friday’s online sales surge is expected to be outdone on Monday, which is Cyber Monday, a promotional event concocted in 2005 when most retailers still offered deep discounts online.

A large portion of consumer spending moved online long before the pandemic, but the global health crisis is accelerating that trend. About 59 percent of shoppers had started their holiday shopping by early November this year, the National Retail Federation estimated.

During earnings calls this month, several retail executives said that they were uncertain about how much holiday shopping had actually been done in October and early November thanks to promotions that started well before Halloween. Matthew Bilunas, chief financial officer at Best Buy, said “it’s really difficult to predict exactly how much was pulled into” the third quarter.

Most retailers operate on a calendar where the fourth quarter starts in November and ends in January, in part to fully capture the holiday shopping season.

“We think it’s going to be a prolonged shopping season,” Brian Cornell, chief executive of Target, said on a separate call. “We’re going to see very different shopping patterns. We don’t expect to see those big spikes during Black Friday and on weekends.”

The holiday shopping season comes at a critical moment for the U.S. economy, which is struggling again as the number of coronavirus cases surges with colder weather in many parts of the country. Millions of people are still out of work or have been forced into part-time employment. Overall consumer spending, which drives as much as two-thirds of economic activity, has slowed in recent months along with the expiration of some emergency government spending programs.

Sapna Maheshwari contributed reporting.