A threatened 50% tariff on Canadian goods has put Michigan's automakers and factory workers on edge, less than a year after the industry began adjusting to the first round of North American trade disruption.

WXYZ 7 News Detroit reported that President Donald Trump's tariff threat is rattling automakers and workers near Detroit, where assembly plants on both sides of the border depend on parts and vehicles that cross the Ambassador Bridge and the Detroit-Windsor tunnel multiple times before a finished car rolls off the line.

The stakes are concentrated in Michigan. The state's automakers — Ford, General Motors and Stellantis among them — build vehicles in Michigan plants using engines, transmissions, stampings and other components sourced from Ontario. Canada's auto sector, in turn, relies heavily on U.S.-built parts. That two-way flow means a 50% tariff would tax the same components repeatedly as they shuttle across the border, compounding costs at each crossing.

Workers in plants around Detroit told the station they fear the tariff could slow production lines and put jobs at risk. The threat lands on a workforce still absorbing the restructuring that followed the shift toward electric vehicles and the uncertainty created by earlier tariff rounds imposed on Canada and Mexico this year.

For Michigan's supplier base, the concern is direct. Tier One and Tier Two suppliers that ship components into Ontario assembly operations would face the tariff on those outbound flows, while Canadian-sourced modules and subassemblies coming into Michigan plants would carry the levy on the return leg. Suppliers typically operate on thin margins under long-term contracts, and few can absorb a 50% duty without renegotiating prices with their OEM customers.

Automakers have not quantified a specific production impact from the threatened tariff, and no plant has announced schedule changes tied to it. The threat remains an announced intention rather than a confirmed policy — it would need to be formalized before manufacturers can price its effect into production plans.

The timing compounds the pressure. Michigan's assembly plants are in the middle of model changeovers and build-out cycles, and any added cost on Canadian-sourced content hits programs already running tight margins. Industry analysts have warned that tariffs at this level on Canada could add thousands of dollars per vehicle in cost, depending on the share of Canadian content, though the final figure depends on how any policy is written and which exemptions apply.

Union officials and plant workers who spoke with WXYZ framed the threat in job terms: production slowdowns, possible shift cuts and pressure on the plants that anchor local economies from Detroit to the surrounding manufacturing corridor.

What to watch next: whether the White House formalizes the 50% tariff and on what effective date, whether automakers respond by shifting sourcing or scheduling downtime at Michigan plants, and whether Ottawa retaliates in a way that further restricts the parts flows that keep Detroit-area assembly lines running.