The total number of coronavirus cases in the United States for November surpassed 4 million today, more than double the record set in October of 1.9 million cases. And the sharp escalation is likely to continue — or grow even steeper.

“We are on track to continue this accelerated pace of the epidemic and see even more speed of rise of cases because of the movement indoors, of activities around the country and because large numbers of people have moved around the country for the holidays,” said Tom Inglesby, director of the Center for Health Security at Johns Hopkins University.

>> PHOTOS: U.S. coronavirus cases surpass 4 million in November

The milestone came as Americans are traveling by the millions for the long Thanksgiving weekend and amid a Black Friday that saw some store crowding, even as merchants tried to guide customers to online sales and limit in-person shopping.

More than 170,000 people in the United States are now testing positive on an average day. More than 1.1 million people tested positive in the past week alone. The country’s overall total, from the start of the pandemic, is more than 13 million infections — by far the world’s largest outbreak.

The Thanksgiving holiday, however, caused skews in reporting at the end of the week, with a steep drop-off in new cases reported Thursday and then a huge jump Friday. Many states did not report data on the Thanksgiving holiday, when the national tally rose by more than 103,000 cases and more than 1,100 deaths — far lower levels than on the previous Thursday, Nov. 19, when 187,000 cases and 1,962 deaths were recorded.

For that very reason, the numbers were artificially high Friday, when many states reported two days’ worth of data. That pushed the country past 200,000 cases in a single day for the first time, with more than 205,000 reported as of late Friday night, along with more than 1,400 deaths. The preceding Friday, Nov. 20, the reports were more than 198,600 infections and more than 1,950 deaths.

The blurry data could persist. Access to testing around the country was likely to have decreased for a few days, meaning more infections could go uncounted. In Louisiana, testing sites run by the National Guard were slated to be closed both Thursday and Friday. In Wisconsin, some National Guard testing sites closed all week.

Many hospitals across the country are already overcrowded and struggling to keep up with rising numbers of patients seeking care, and the pressure on the health care system is likely to only increase.

The country’s monthly case numbers have varied considerably but have exploded over the past two months. Officials announced more than 188,000 cases for the month of March, followed by a significantly higher 887,000 cases for April. From there, the monthly total dropped to more than 723,500 for May, and then, after the Memorial Day holiday, rose to more than 854,000 for June. That skyrocketed to more than 1,918,000 for July, dropped to more than 1,473,000 for August and more than 1,216,000 for September, and then shot back up past 1,946,000 for October.

The number for this month, as of midday Saturday, was 4,006,548, with more than two days left for the tally to grow.

Monthly deaths have been rising more slowly, but they are already higher than at any point since the spring surge, when New York, New Jersey and Louisiana became global hot spots.

News of the likely approval of at least one vaccine in mid-December has raised hopes that the virus can be slowed, but until a significant proportion of the population can be vaccinated, experts say, people need to act responsibly. And, they say, officials should add or create rules that discourage indoor and group gatherings.

“There has to be a combination of individual members of the public making different decisions and policymakers restricting the activities or settings with highest transmission risk, like restaurants and bars, where people are sitting close for prolonged periods without masks,” said Inglesby.

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