Washington — What began as an effort by former President Donald J. Trump to apply economic pressure on Canada is increasingly being reassessed in Washington, as lawmakers from border states warn that the strategy is producing unintended consequences at home.

In recent weeks, members of Congress representing districts along the U.S.–Canada border have raised concerns that tariffs and confrontational trade rhetoric are dampening cross-border commerce, tourism and local business activity. Their warnings mark a notable shift in tone, with criticism coming not from Ottawa, but from within the United States itself.

The concerns center on a visible decline in Canadian travel to the United States, particularly in communities that rely heavily on cross-border visitors. Ferry operators, retailers and hospitality businesses in parts of New York, Michigan, Washington and Maine have reported softer demand, which local officials attribute to a mix of higher costs, uncertainty and changing consumer sentiment in Canada.

“This isn’t theoretical anymore,” said one Democratic lawmaker from a northern border district. “Our towns depend on Canadians coming across to shop, vacation and spend money. When relations sour, those trips are the first thing to disappear.”

Data from tourism authorities suggest a measurable slowdown in some regions, though analysts caution that multiple factors are at play, including exchange rates and broader economic conditions. Still, the timing has intensified scrutiny of trade policy choices and their localized effects.

The pushback in Congress reflects growing unease over how trade disputes ripple through interconnected economies. Canada is the United States’ largest export market and its closest trading partner, with supply chains that span energy, agriculture, manufacturing and services. Even modest disruptions can have outsized effects in border regions where economic integration is deepest.

Canadian officials have largely avoided public confrontation, but Ottawa has responded with a more inward-looking economic posture. Prime Minister Mark Carney has emphasized domestic resilience and encouraged consumers and institutions to prioritize Canadian suppliers where possible. While framed as an economic stability measure rather than retaliation, the shift has been noticed in Washington.

Behind the scenes, Canadian policymakers have moved to reinforce domestic supply chains and reduce exposure to sudden policy shifts south of the border. According to people familiar with the discussions, federal and provincial officials have coordinated messaging around economic self-reliance, particularly in sectors sensitive to U.S. tariffs.

In Congress, the evolving situation has prompted lawmakers to urge a recalibration. Several have warned that prolonged trade tensions risk alienating a partner whose economic behavior can directly affect American communities. “You can talk tough in Washington,” said a Republican representative from the Midwest, “but when that toughness empties main streets back home, voters notice.”

The Trump administration has defended its approach as necessary to correct trade imbalances and protect American industry. Supporters argue that short-term pain is an acceptable cost for long-term leverage. Critics counter that the strategy underestimates how quickly consumers and businesses adapt, especially in allied countries with alternatives.

Economists note that consumer behavior is often the earliest indicator of shifting relationships. “You don’t need formal sanctions for impact,” said a trade economist at Georgetown University. “When people feel unwelcome or uncertain, they change habits. That can happen quietly but decisively.”

Online, the debate has intensified. Reports of struggling border towns and reduced Canadian travel have circulated widely, fueling partisan arguments over responsibility and strategy. While some of the claims have been exaggerated, the underlying concern has resonated beyond political circles.

For Mr. Carney, the moment has reinforced his emphasis on economic risk management. A former central banker, he has framed diversification and domestic capacity as insurance against volatility rather than a rejection of the United States. “Canada’s prosperity depends on openness,” he said recently, “but also on resilience.”

U.S. officials insist that the bilateral relationship remains strong and that disagreements can be resolved. Yet the growing chorus from border-state lawmakers suggests that patience is wearing thin. Trade policy, they argue, must account not only for national leverage but for local consequences.

Whether the current tensions will ease remains uncertain. Negotiations continue, and neither side has signaled a desire for escalation. But the episode has underscored how quickly pressure tactics can rebound in deeply integrated economies.

As Congress debates next steps, the lesson emerging from border communities is clear: in a trade war between close neighbors, the effects rarely stop at the border. They seep into daily life, reshaping behavior long before policy shifts catch up.

In that sense, the unfolding situation has become less about winners and losers than about interconnectedness — and the challenge of using economic pressure without damaging the very communities policymakers aim to protect.