On Monday, thousands of visitors from across the country descended on Yellowstone national park, which opened for the first time since its closure in March due to the coronavirus pandemic.

“We have been cooped up for weeks,” Jacob Willis told the Guardian near a crowd of onlookers at the Old Faithful Geyser. “When the parks opened, we jumped at the opportunity to travel,” said Willis, who had arrived from Florida.

Yellowstone, America’s oldest national park, and the nearby Grand Teton national park are the most recent to have partially reopened with the support of the Trump administration.

“I hope everybody is listening,” Donald Trump announced earlier in May. “The parks are opening, and rapidly, actually.”

While many have celebrated the reopening of the revered landscapes, others have raised health concerns about large, possibly maskless, groups of out-of-state visitors arriving and potentially skirting social distancing guidelines.

“We checked the webcam at Old Faithful at about 3.30pm yesterday,” said Kristin Brengel, the senior vice-president of government affairs at the National Parks Conservation Association. “Not much physical distancing happening and not a single mask in sight.”

“I think we’re the only car from Teton county,” said Mark Segal, a Wyoming local, noting the prominence of out-of-state license plates in Yellowstone on Monday.

At the Moran entrance station in Wyoming – the entrance to both Grand Teton and Yellowstone park – cars began to line up at 5.30am. By 11am, an hour before opening, vehicles with license plates from as far away as New York, Washington State and Alaska sprawled along the highway leading to the park entrance.

Park fees were waived and masked rangers cheerfully welcomed visitors who streamed through the gate.

Many of the visitors drove directly to Old Faithful, Yellowstone’s most popular attraction, to watch the 2.20 geyser eruption. The Guardian witnessed rangers having to disperse large groups of onlookers twice.

Amy, a 19-year-old from San Diego, traveled to Yellowstone with four college friends. They planned to visit many of the parks that have recently reopened.

“We wanted to get out and see the country,” said Amy, as hundreds of visitors sat on the semi-circle of benches that surround Old Faithful.

According to the National Park Service, Yellowstone’s phased reopening includes a ban on tour buses, overnight camping and lodging. Only the Wyoming gates into the park are currently open, and the park will provide protective barriers “where needed” and encourage “the use of masks or facial coverings in high-density areas”.

“The park’s goal is to open safely and conservatively, ensure we take the right actions to reduce risks to our employees and visitors, and help local economies begin to recover,” said the Yellowstone superintendent, Cam Sholly.

For Segal, who came on opening day in hopes of a quiet Yellowstone experience, the number of out of state visitors was disturbing.

“What if everyone that leaves here goes and gets a bite in Jackson?” he asked, referring to a nearby town and speaking to the Guardian from his car as he and his family waited to get into the park. “This is exactly what we’re afraid of.”