When President Donald Trump declared that the United States did not need Canadian lumber, the remark was delivered with characteristic certainty. “We have more lumber than they do,” he said, framing the issue as one of national self-sufficiency.

Soon after, his administration imposed new tariffs on imported softwood lumber, including duties that reached as high as 25 percent on certain Canadian products. The policy, officials said, was designed to protect American mills and workers from what Washington has long argued are unfair Canadian subsidies tied to provincial forestry systems.

The move revived a decades-old trade dispute between the two countries. Yet it also reignited a practical question that has complicated efforts at economic nationalism: How easily can the United States replace a supplier that accounts for nearly one-third of the lumber used in its home construction?

For generations, Canadian softwood has flowed south across one of the world’s longest land borders, feeding American demand for single-family homes, apartment buildings and infrastructure projects. Geography, compatible building standards and integrated supply chains have made the partnership efficient, if periodically contentious.

When tariffs took effect, the immediate impact was visible in lumber futures markets. Prices climbed sharply, adding to volatility already fueled by pandemic-era disruptions and a surge in housing demand. The National Association of Home Builders estimated that duties on Canadian lumber added thousands of dollars to the cost of constructing a typical single-family home.

Builders felt the strain quickly. Many operate on narrow margins, and lumber represents a core input in residential construction. As costs rose, some developers passed them on to buyers. Others delayed projects, waiting for price stability that proved elusive.

Domestic sawmills initially welcomed the protection, arguing that tariffs would allow them to expand production and invest in capacity. But scaling up output is not immediate. Expanding timber harvests and mill operations requires regulatory approvals, labor and capital investment — processes measured in years, not months. In the interim, supply tightened.

By 2021, lumber prices reached record highs, quadrupling from pre-pandemic levels at one point. While multiple factors drove the spike — including supply-chain bottlenecks and elevated demand — economists and housing analysts said trade policy added pressure in an already overheated market.

Higher lumber prices rippled beyond construction sites. Furniture manufacturers reported increased costs. Packaging and paper producers, linked to broader forestry markets, saw input prices fluctuate. The cumulative effect contributed modestly to broader inflation trends during a period when consumer prices were rising across sectors.

The Federal Reserve, in public remarks and policy discussions, cited supply constraints and commodity volatility — including lumber — as among the contributors to price instability. Although tariffs were not the sole cause, they became part of a broader narrative about the unintended consequences of trade barriers in tightly integrated markets.

Canada, meanwhile, sought to mitigate the impact by diversifying exports. Producers expanded shipments to Asia and Europe, and provincial governments invested in higher-value engineered wood products and sustainability initiatives. While the United States remained an essential market, reliance on a single buyer appeared less secure.

The dispute also exposed political crosscurrents in Washington. Some lawmakers from timber-producing states supported the tariffs, viewing them as overdue enforcement of trade rules. Others, particularly those representing fast-growing regions with acute housing shortages, questioned whether the policy’s benefits outweighed its costs to consumers.

One senator, speaking during a committee hearing, remarked that the country had “built walls out of tariffs, not homes out of lumber,” capturing the tension between industrial protection and housing affordability.

At the core of the debate lies a structural reality: The United States possesses vast forest resources, but domestic production has not consistently met demand for softwood lumber used in residential framing. Environmental regulations, wildfire risks and land-use policies shape the pace and scale of harvesting. Canadian forests, particularly in British Columbia and Alberta, have filled that gap for decades.

Trade experts caution that the dispute is unlikely to disappear soon. Softwood lumber has cycled through rounds of litigation under the North American Free Trade Agreement and its successor, the United States-Mexico-Canada Agreement. Each episode has produced temporary settlements, followed by renewed disagreement over pricing and subsidy calculations.

Mr. Trump’s assertion that America does not need Canadian lumber resonates politically with voters drawn to the language of self-reliance. Economically, however, the picture is more complex. Integrated supply chains mean that abrupt shifts can carry domestic costs, particularly in sectors as sensitive as housing.

Today, home prices remain elevated in many regions, shaped by interest rates, labor shortages and land constraints as much as by material costs. But the lumber dispute serves as a reminder that trade policy, even when targeted at foreign producers, often reverberates at home.

As negotiations and legal challenges continue, builders and buyers are left navigating uncertainty. The question is no longer simply whether the United States can produce more lumber. It is whether, in an interconnected market, disentangling from a longstanding partner can be achieved without reshaping the economics of homeownership itself.