At the end of a waitressing shift, Kristina Lampert used to separate her tips in two piles: Canadian cash and American.

But it’s been weeks since she has done that.

Freighters, the restaurant where she works, is one of the first places people can grab a bite after crossing the US-Canada border between Sarnia, Ontario, and Port Huron, Michigan.

The Blue Water Bridge, which connects the US and Canada, is in full view from the restaurant’s windows.

“A lot of people used to come over and say ‘we’re here for the view’,” she says of Canadian diners. “I haven’t heard that at all recently.”

Border towns noticed almost instantly when US President Donald Trump began imposing tariffs on countries around the world and saying he wanted to make Canada the 51st US state – because the number of Canadians crossing the border plummeted.

Border crossings between the US and Canada are down some 17% since Trump started bringing in tariffs, according to CBP data.

Canadians car trips to the US are down almost 32% compared to March 2024, according to Statistics Canada.

Like many of the towns that dot along the 5,525 mile (8,891 km) border, the economies of Port Huron and Sarnia are linked and in some ways dependent on one another. Port Huron is a manufacturing town of less than 30,000 people with a quaint downtown and lots of retail, offering visitors an enticing opportunity for a day-trip.

On a day where there is little traffic, a Sarnia resident can cross the border and be in Michigan in a matter of minutes.

Many of these towns faced their first test more than five years ago when the Covid-19 pandemic shut crossings down for 19 months and left local economies reeling.

Now, they are seeing a second economic hit due to Trump’s trade war, with many Canadians choosing to “Buy Canadian” – purchase Canadian-made goods – and reducing travel to the US in response to the fraying relationship between the two neighbouring countries.

One place this is being felt is at Sarnia’s Duty Free, the last place you can purchase goods before leaving Canada and entering the US. The shelves of perfume and liquor are fuller and the parking lot is emptier since tariffs tensions began.

Barbara Barett, the executive director of Frontier Duty Free Association, says some of the 32 land-border duty frees in Canada have seen as much as an 80% decrease in sales since Trump’s return to the White House. Most stores have seeing a 50-60% drop in business.

“We’re 100% reliant on the travel across the border,” she says of duty frees. “Our stores are often pillars of these communities; communities depend on them.”

And while the crossing at Port Huron-Sarnia is faring better than most, on a Friday in May the parking lot of the Sarnia Duty Free is almost empty.

Tania Lee, who runs the store with her family, says that has become the new norm.

On Easter weekend – usually one of their busiest of the year, as Canadians take advantage of the break to stop in at a favourite restaurant and go to a church service in Port Huron – cars were few and far between and sales were not what they should have been, she says.

“We are suffering because of collateral damage at the border,” Ms Lee says of her second-generation family business.

Ms Lee notes that people who live in border towns often cross the boundary multiple times a week. She, for example, has a mailbox at a shipping facility in Port Huron that she visits regularly, as do her neighbours.

People across the Blue Water Bridge are feeling the effects too, Mayor Anita Ashford says.

She has heard from both residents of her town and Canadians frustrated about the increased tension between the nations.

Nationally, a 10% drop in Canadian tourism would cost the US up to 14,000 jobs and $2.1bn (£1.56b) in business, according to the US Travel Association.

Michigan is one of the places likely to see the brunt of that impact. In 2023, Canadians visitors spent a collective $238m in the state, according to tourism officials.

That money is essential for border towns like Port Huron, its mayor says.

“I hope people in Washington will start to understand what they’re doing to the people,” she says. “We are not responsible for this, the [federal] government put us in this position and now we have to deal with it respectfully.”

“We need each other,” she says.