A USA Today analysis of cell phone data found some 400 ZIP codes where foot traffic at businesses more than doubled from the previous weekend. The data, supplied by location data company SafeGraph, included the first two days of the long holiday weekend.

People at Missouri's Lake of the Ozarks drew a scolding from across the Internet Memorial Day weekend after images of shoulder-to-shoulder partiers in a swimming pool went viral.

It turns out the lakefront wasn’t the only place to draw a huge influx of holiday visitors to its hotels, restaurants and stores.

A USA Today analysis of cell phone data found some 400 ZIP codes where foot traffic at businesses more than doubled from the previous weekend. The data, supplied by location data company SafeGraph, included the first two days of the long holiday weekend.

Although the data can’t tell whether people clumped together in ways on display at Lake of the Ozarks, they show the drive to recreate was widespread.

The list of hotspots was filled with waterfront resort towns, national landmarks and destination casinos spread from Lake Erie to the Grand Canyon, from the Gulf of Mexico to the Outer Banks of North Carolina, from Lake George in upstate New York to inland lakes across the South.

Almost a third of the 400 actually received more foot traffic than Memorial Day 2019, long before anyone dreamed of an illness called COVID-19.

All but three states -- Connecticut, Delaware and Massachusetts -- had at least one ZIP code with a massive increase in business visitors.

“Clearly, there were many, many people who just threw off the halter and decided they were not going to do any semblance of social distancing, at least for that weekend,” said William Schaffner, an infectious disease doctor and professor at Vanderbilt University School of Medicine. “These are the circumstances that COVID– 19 looks forward to.”

Other health experts warned that the movement of people from cities to smaller resort towns risked fresh outbreaks. Most of the counties with Memorial Day hotspots reported comparatively low infection rates as of Friday before the holiday, according to USA TODAY'sdatabase of coronavirus case counts.

In the majority of the 19,000 U.S. ZIP codes for which reliable cell phone data were available, foot traffic to businesses fell over the holiday weekend from the weekend before.

Traditional vacation hotspots were a stark contrast. 

Cell phone data showed ZIP codes around Lake of the Ozarks had huge increases in foot traffic, as one would gather from images on social media. But the numbers were still down from last year.

Moreover, the surge at the Missouri lake was far from the biggest in the country. Some 90 ZIP codes had bigger week-over-week increases in foot traffic than the main Lake of the Ozarks magnet, ZIP code 65072.

Places that beat 65072 notably included parts of rural New England, such as the shore of New Hampshire’s Lake Winnipesaukee.

No place witnessed a bigger surge of activity than 2.2-million-acre Yellowstone National Park, just as ZIPS adjacent to Mount Rushmore and the Grand Canyon showed major growth from the prior weekend. The National Park Service has started re-opening many such locations in phases.

Statistics from the federal agency confirmed what cell phone data suggested for Yellowstone, America’s oldest national park.

Although snow closed the park on Saturday, vehicle traffic in Yellowstone’s southern half nearly matched last year’s Sunday-Monday total: More than 4,500 vehicles entered through the park’s two Wyoming gates.

Stan Werkema, manager of the Old Faithful General Store, said the area outside was bustling over the holiday while workers in the store itself prepared it for opening this week.

“People want to go out. What is a better place to get out to than Yellowstone National Park?” Werkema said.

Five zipcodes around Oklahoma’s 60-mile-long Grand Lake were among those with huge retail traffic increases.

Eddy’s Lakeside Bar, part of the Shangri-La resort, had people lined up waiting for a seat for 14 hours a day, noon until 2 a.m., until rain hit on Monday, director of communications Mike Williams said.

The bar was alone in offering live music at the lake over the weekend, which may have contributed to people lining up for seats.

Management placed tables six feet apart and removed two-thirds of the bar stools, among other measures, Williams said.

Williams guessed about half the patrons were happy to see the precautions, while the other half thought they were unnecessary.

Was it enough?

“I guess we’ll know in two weeks, right?” he said, alluding to a typical period for COVID-19 symptoms to emerge after infection.

Elsewhere in Oklahoma, ZIP code 74366 had more traffic than Memorial Day 2019.

A major source of the increased activity: the Salina Highbanks Speedway.

The track’s website listed the “Allen Frailey Memorial Race and Custom Coatings Appreciation Night” for Memorial Day Saturday, an event that promised a free hot dog to the first 550 spectators in the stands.

In Ohio, at the Lake Erie island of Put-in-Bay, docks were full, the boardwalk bustling over the weekend. Hotels reported occupancy of 60 to 70 percent, said Peter Huston, director of the island’s chamber of commerce.

Bill Market, co-owner of Miller Ferries, said the company’s three vessels carry hundreds but reduced capacity by about a third for safety. Crew members sanitized high contact areas such as handrails and benches between each trip.

“We rely on the tourist industry to survive the whole season,” Market said. “There’s no doubt there’s risk involved, but I think for the most part people are anxious to get out.”

In some places travel was largely limited to day trips. But even that could have its problems, according to William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health.

Consider Lake George, in the Adirondacks of upstate New York. About 90% of visitors to the area came from within the state, USA TODAY found -- including 17% from the New York metro, among the areas hardest hit by COVID-19 nationwide. 

“Movements from places where we know there’s a high population prevalence to a low give the opportunity to introduce it where it’s currently not common,” Hanage said.

In Arizona, where the biggest increase in foot traffic was in zip codes near the entrance to the Grand Canyon, the tiny town of Jerome also experienced a spike in traffic.

Located 110 miles north of Phoenix and a popular day trip destination, , Jerome received 90% of its Memorial Day visitors from within Arizona, the SafeGraph data show.

The historic Connor Hotel, even with a new requirement that guests stay a minimum of two nights, was completely booked all weekend. The hotel reopened May 16 with new coronavirus safety protocols. Rooms would stay vacant 24 hours after a guest left. Only two visitors are allowed in the lobby at a time, and they must wear face coverings.

Monica Medina, who runs the front desk at the hotel, said she saw Phoenix residents escaping the heat as well as visitors from California and Colorado.  Both are a few hours’ drive from Jerome.

“They’re traveling but they’re staying close to home. They’re taking trips they can just drive to,” Medina said.

Rex Peters, manager of the Jerome Artists Cooperative Gallery, said the town was very crowded all weekend. Visitors, he said, were practicing appropriate distancing and wearing masks.

Still, he has yet to reopen his gallery, a popular showcase of local artists. He is hopeful that could happen by July.

“We’re an artist cooperative, so we’re mostly old people with varying degrees of underlying health conditions,” he said. “Nobody is in a hurry to open and get in the midst of it.”

Contributing: USA TODAY Network reporters Karen Weintraub, Ellie Melero, Melissa Yeager, Eric Lagatta, Philip Drake, Greg Holman, Trevor Mitchell, Dennis Wagner.