David McMillan, the co-owner of Montreal's famed temple of gluttony, Joe Beef, used to spend his days obsessing over his signature dishes such as lobster spaghetti and rabbit with mustard sauce. These days, however, he has another preoccupation: studying American vaccination rates.

Before the pandemic, so many American gastronomy pilgrims from New York, Boston and Los Angeles came each week to Joe Beef that many local residents, facing a 10-week waiting list, all but gave up trying. The Americans, McMillan recalled wistfully, thought nothing of buying expensive bottles of Champagne and sucking down oysters until midnight, before buying his prophetic-sounding cookbook "Surviving the Apocalypse."

"Ah, how I miss the Americans," said McMillan, who presides over a mini-empire of four restaurants in the city. American tourists, he added, accounted for half of Joe Beef's pre-pandemic weekly revenue of about $118,000. "When the Americans were here every night it felt like we were putting on a Broadway show."

"Now, I look every day at how the U.S. vaccination is going," he added. "And I get messages every day from American clients asking when they can get back in."

It's a question many in the Canadian tourism industry have also been asking, ever since the Canada-U. S. border was closed to nonessential travelers in March. The loss of American visitors, armed with their strong dollars and consuming zeal, has buffeted popular destinations such as Montreal, Quebec City and Vancouver, already reeling from a debilitating pandemic. Canadian airlines have been forced to make thousands of layoffs.

More than two-thirds of the 21 million international tourists who came to Canada in 2019 were from the United States, according to government data, with Americans pumping about $8.7 billion into the economy.

Absence makes the heart grow fonder — but not enough to open borders.

The inauguration of President Joe Biden and Vice President Kamala Harris, who spent her disco-dancing teenage years in Montreal, has renewed the ardor between the two allies, while vaccination has created cautious optimism about taming the pandemic.

Still, while the tourism industry is experiencing one of its worst crises since World War II, recent polls show that the vast majority of Canadians want the borders to remain closed.

Mélanie Joly, Canada's minister of economic development, who is responsible for tourism, said keeping the borders closed was a matter of pragmatism. "We can't talk about reopening the economy until we stop the spread of the virus," she said.

She said she hoped the travel industry would be "back on its feet" by September, as vaccination in Canada and the United States accelerated. The border, she stressed, would remain closed until the pandemic is contained.

MacMillan, of Joe Beef, said the loss of the Americans, while painful, also had some advantages, allowing the restaurant to reconnect with local residents, who have been ordering takeout while indoor dining is banned. Without having to cater to the sometimes squeamish culinary tastes of his American guests, he has brought back some of his favorite items, like pig cheeks and kidneys.

In British Columbia's pristinely beautiful Okanagan Valley, an ascendant wine region that draws American tourists from across the West Coast, John Skinner, owner of Painted Rock Estate Winery, lamented that not being able to host American weddings on the grounds of his winery, or to attract American oenophiles, had dented business.

But he said that the loss of the Americans has been more than offset by the proliferation of Canadians doing staycations.

"The hotels and restaurants have been full of Canadian wine-tourists, so I can't say we have missed the Americans." He quickly added: "We love Americans. But they can come visit us when they are all inoculated and we are, too."