Canada’s border is back open this week for vaccinated U.S. tourists. For Canada, Americans are big business: Before the pandemic, more tourists from the U.S. visited Canada than from any other country. That was also true in the reverse; Canadians were America’s top visitors.

So what does it mean that Canada is open while, for now, the U.S. stays closed?

More than a quarter of tourists to the U.S. used to come from Canada. Roger Dow would see them every winter in Florida.

“I can tell when the Canadians are in town because all the condo lights light up,” Dow said.

Dow is CEO of the U.S. Travel Association, and now that Canada’s border is open, he said the U.S. should return the favor. If not, he said, Canadians may choose other destinations.

“Travel is like water, it will go to the place where it’s easiest to go to, and if there’s a block, it will go somewhere else,” he said.

Besides snowbird locations, U.S. border towns, from Washington state to Maine, depend on Canadians.

Once the border reopens, Canadians will come back, said University of Central Florida hospitality professor Alan Fyall.

“It’s easy to get here. They’ve got so many family connections. It’s such an ingrained relationship that it, it’s still gonna be there,” Fyall said.

U.S. border restrictions are set to expire later this month, and Fyall said Canada’s reopening puts pressure on the U.S. not to extend those.