How CUSMA/USMCA Works

The Canada–United States–Mexico Agreement, known in Canada as CUSMA and in the United States as the USMCA, is the single most important framework governing Canada’s economy beyond its borders. The United States buys the large majority of what Canada sells abroad, and CUSMA sets the rules under which most of that trade flows. Understanding how it works — and what its built-in review could change — is essential to understanding Canada’s economic exposure.

Background

CUSMA replaced the North American Free Trade Agreement (NAFTA), which had governed continental trade since 1994. After the 2016 U.S. election, the American administration sought to renegotiate NAFTA, and the three countries agreed on a successor in 2018. CUSMA was signed in late 2018, amended in December 2019 to satisfy concerns in the U.S. Congress over labour and enforcement, and entered into force on July 1, 2020.

In substance, CUSMA preserved the core of NAFTA — tariff-free trade in most goods across the three countries — while tightening rules in several areas and adding new chapters on subjects that barely existed in 1994, such as digital trade.

Key actors

The agreement binds three governments: Canada, the United States, and Mexico. In Canada, trade policy is led by the minisries responsible for international trade and finance, supported by Global Affairs Canada; major decisions involve the Prime Minister’s Office given the stakes. Provincial governments matter too, because many affected sectors — from dairy to autos to forestry — are regulated provincially or concentrated in particular provinces.

Industry groups, unions, and the auto sector are unusually influential in CUSMA politics, because the agreement’s most contested rules touch manufacturing supply chains that cross all three borders many times before a finished product is sold.

What changed from NAFTA

Several changes stand out. Automotive rules of origin were tightened: to qualify for tariff-free treatment, a vehicle must now contain a higher share of North American content — 75 percent regional value, up from 62.5 percent under NAFTA. CUSMA also added a labour value content rule requiring that a substantial share of a vehicle be made by workers earning at least US$16 per hour, a measure aimed at shifting some production away from low-wage plants.

The agreement strengthened labour and environmental enforcement, including a novel mechanism allowing rapid response to alleged labour-rights violations at specific facilities. It added a modern digital trade chapter barring customs duties on electronic products and limiting data-localization requirements. It preserved a form of dispute settlement between states, while changing the investor-state provisions that had been controversial under NAFTA.

For Canada specifically, the agreement granted the United States expanded access to the Canadian dairy market under the supply-management system — a politically sensitive concession — while retaining the cultural-industries exemption Canada has long defended.

Numbers

The United States is overwhelmingly Canada’s largest trading partner, typically accounting for roughly three-quarters of Canadian merchandise exports. Two-way trade in goods and services across the Canada–U.S. border runs into the high hundreds of billions of dollars each year, and millions of Canadian jobs are linked directly or indirectly to that trade. Mexico is a smaller but growing partner. This concentration is precisely why CUSMA’s rules — and the stability of the U.S. relationship — carry such weight.

Policy stakes

The defining feature of CUSMA is its review-and-sunset mechanism. Unlike NAFTA, CUSMA has a 16-year lifespan with a built-in joint review scheduled six years after entry into force — that is, in 2026. At that review, the three countries decide whether to extend the agreement for a further 16 years. If they cannot agree to extend, the agreement enters a path toward expiry, with annual reviews until it would lapse.

This design was meant to force periodic re-examination rather than letting the agreement drift. In practice it means that, every several years, the rules underpinning the majority of Canada’s exports are formally reopened for negotiation — creating both leverage and uncertainty. The 2026 review is the first real test of that mechanism, and its outcome will shape the predictability of Canada–U.S. trade for years.

Beyond the review, recurring flashpoints include U.S. tariff threats on specific sectors, disputes over softwood lumber and dairy, and pressure on Canada to align its trade and investment screening with U.S. policy toward third countries. For an export-dependent economy, the central policy question is always the same: how to preserve secure access to the U.S. market while reducing the risk that comes from depending on a single partner.

Reading list

The full text of CUSMA and the official summaries published by Global Affairs Canada
The 2019 protocol of amendment and the labour and enforcement provisions
Canadian government backgrounders on automotive rules of origin
Parliamentary Budget Officer and committee analyses of CUSMA’s economic effects
Trade-policy research on the 2026 joint review and sunset clause