Auto Tariffs in 2026: What Detroit Shippers Actually Need to Know Right Now

If you move auto parts across the Detroit-Windsor corridor, the last 60 days have rewritten the rules you were operating under — and the next 90 days are going to rewrite them again.

On February 20, the U.S. Supreme Court struck down the tariffs President Trump had imposed under the International Emergency Economic Powers Act. Four days later, the administration replaced them with a temporary 10 percent tariff under Section 122 of the Trade Act of 1974. That tariff expires on July 23. One week before it does, on July 1, the first formal joint review of the USMCA begins — the mandatory six-year check-in that will determine whether the agreement gets extended, renegotiated, or allowed to sunset.

Three separate trade-policy events, all converging on the same calendar month, all landing directly on the desk of anyone routing automotive freight through Michigan. This is not a policy-wonk story. This is a cost-per-part story, and if you’re not already running the numbers, you’re behind.

What the Supreme Court Actually Ruled

The Supreme Court’s February 20 decision was a 6–3 ruling authored by Chief Justice Roberts. The core finding: IEEPA — the International Emergency Economic Powers Act — does not authorize the president to impose tariffs. The statute grants emergency powers over international economic transactions, but the Court held that tariffs are a fundamentally different instrument, one that belongs to Congress under the Constitution’s Import-Export Clause.

The practical effect was immediate. The IEEPA tariffs that had been layered across a broad range of imports — including many that touched the automotive supply chain — were struck down. Importers who had paid those duties are now eligible for refunds, and the government has begun accepting applications.

Here’s the catch: the ruling didn’t eliminate tariff exposure. It shifted the legal foundation underneath it.

Section 122: The Replacement Tariff

Within four days of the ruling, the administration imposed a 10 percent tariff under Section 122 of the Trade Act of 1974 — a statute designed to address “fundamental international payments problems.” The tariff took effect on February 24, 2026.

Section 122 has a hard statutory limit: 150 days. That puts the expiration at July 23, 2026. Congress can vote to extend it, but absent that vote, the tariff disappears automatically.

For automotive specifically, the net tariff change from IEEPA to Section 122 was modest — roughly 6.3 percent down to 5.6 percent on finished automobiles. The reason: Section 232 tariffs on automobiles and auto parts (imposed on national security grounds) remain in force and are separate from both IEEPA and Section 122. Products already covered by Section 232 are exempt from the new Section 122 duties.

What this means in practice: if you’re shipping auto parts that fall under Section 232, your duty exposure didn’t change much. If you’re shipping components that were caught by IEEPA but aren’t covered by Section 232 — certain raw materials, specialty tooling, electronics subassemblies — your cost structure just shifted, and you need to know which direction.

The USMCA Review: July 1, 2026

This is the one that should be keeping logistics planners up at night.

Article 34.7 of the USMCA establishes a mandatory joint review six years after the agreement entered into force. That review begins July 1, 2026. All three parties — the United States, Mexico, and Canada — must decide whether to confirm the agreement for another 16-year term, negotiate revisions, or allow the pact to begin its sunset countdown.

The U.S. Trade Representative has already opened a formal comment period on automotive goods under the USMCA, and must submit a report to the Senate Finance Committee and House Ways and Means Committee by July 1. The USITC has launched a full review of automotive rules of origin, with particular focus on the 75 percent regional value content threshold — the rule that determines whether a vehicle qualifies for duty-free treatment under the agreement.

Trade analysts are projecting three plausible scenarios:

Scenario 1 — Straight extension. All three parties agree to extend the USMCA through 2042 without major changes. This is the most optimistic outcome and the least likely, given the current trade environment.

Scenario 2 — Negotiated revisions plus extension. This is the consensus expectation. Revisions would likely include tighter automotive content rules, new provisions for EVs and critical minerals, restrictions on Chinese-affiliated manufacturing within USMCA countries, and enhanced labor enforcement mechanisms. The agreement gets extended, but the terms change — and those term changes directly affect rules-of-origin calculations for every auto part crossing the border.

Scenario 3 — No consensus. If the parties can’t agree, the USMCA enters a rolling review cycle. The agreement doesn’t immediately terminate, but the uncertainty it creates is its own cost — carriers price it in, customs brokers flag it, and supply chain planners have to model for a world where the agreement may not exist in its current form by 2036.

Why Detroit Is Ground Zero

Michigan doesn’t just participate in the cross-border auto parts trade. Michigan is the cross-border auto parts trade.

The Detroit-Windsor corridor is the single highest-value commercial crossing in North America. The Ambassador Bridge and the Detroit-Windsor Tunnel together handle a share of U.S.-Canada surface trade that is wildly disproportionate to their physical footprint. The Gordie Howe International Bridge — which I covered in detail in my last briefing — is on track to open later this year, adding capacity but also introducing its own set of ownership and toll-structure uncertainties tied to the same U.S.-Canada trade tensions driving the tariff conversation.

The numbers tell the story of exposure. The average car contains nearly 30,000 individual parts. Approximately 40 percent of those parts are imported. Mexico is the largest foreign supplier, holding a 46.3 percent share of U.S. auto parts imports, with roughly 87 percent of Mexico’s auto parts exports destined for the United States.

The Detroit Big Three — General Motors, Ford, and Stellantis — collectively absorbed $6.5 billion in tariff-related costs in 2025 alone. Industrywide projections put the total tariff burden on automakers at $35.4 billion since the current tariff regime began. The projected forward impact: $42 billion in costs affecting 6.8 million vehicles in production volume.

The Detroit Regional Chamber, through its automotive arm MichAuto, joined a national trade alliance on April 15 specifically to push back on tariff policies and advocate for consistent, predictable trade rules. Glenn Stevens, MichAuto’s executive director, has been direct about the stakes: Michigan’s businesses are disproportionately impacted, and the uncertainty is as damaging as the duties themselves.

What This Actually Costs at the Border

Let me translate the policy into the freight math that matters to the operators I work with.

Customs brokerage complexity is up. Every shipment crossing Detroit-Windsor now requires classification against three overlapping tariff regimes: Section 232 (national security), Section 122 (temporary surcharge), and whatever USMCA preferential rate the part qualifies for. A single auto part can be subject to different duty rates depending on which legal authority applies. Customs brokers who were already stretched thin are now running triple-classification checks on every entry. If your broker isn’t doing this, you’re exposed.

Duty drawback and refund opportunities are open — but time-limited. For importers who paid IEEPA duties before the Supreme Court ruling, the window to file for refunds is open now. For liquidated entries, you have 180 days from the liquidation date to file a protest. For open entries, monitor for the liquidation date and act accordingly. This is not a “we’ll get to it” situation — these are hard deadlines, and the money left on the table is significant.

Transit time variability at the crossings is increasing. When customs classifications get more complex, processing times at the border increase. Anecdotally, we’re seeing 15 to 30 additional minutes per crossing at the Ambassador Bridge during peak hours compared to six months ago. That’s not dramatic on a single truck. Multiply it across a fleet running 40 crossings a day, and you’re looking at measurable drayage cost increases and appointment window misses on the other side.

Carrier pricing is absorbing uncertainty. Cross-border carriers can’t price a lane when they don’t know what the tariff structure will look like in 90 days. The response is a volatility premium — rates are higher than the underlying cost structure would justify, because carriers are hedging against a July that could go any of three directions. An estimated 100,000 truckers are directly affected by cross-border freight disruptions, hauling 85 percent of surface trade with Mexico and 67 percent with Canada.

What to Actually Do About It

If you’re routing auto parts through Detroit right now, here’s the playbook I’m giving my clients:

Audit your customs entries immediately. If you paid IEEPA duties at any point in the last 18 months, check whether those entries have been liquidated. If they have, file your protest before the 180-day window closes. If they haven’t, flag them for monitoring. The refund amounts are not trivial — for high-volume importers, we’re talking six and seven figures.

Run a USMCA scenario model before July. Don’t wait for the review outcome to plan for it. Model three scenarios — straight extension, revised rules of origin, and no-consensus uncertainty — and map each one against your top 20 parts by volume. Know which parts lose preferential treatment under tighter content rules, and know what your duty exposure looks like if they do.

Re-evaluate your crossing strategy. The Gordie Howe Bridge opening later this year adds a third crossing option to the Ambassador Bridge and the tunnel. Each crossing will have different throughput characteristics, different toll structures, and different customs processing realities. If you’re defaulting all your Detroit-Windsor freight to one crossing without running the math, you’re leaving money and time on the table.

Talk to your customs broker about Section 122 expiration planning. July 23 is 98 days away. If Section 122 expires without congressional extension, your cost structure shifts again. If Congress does extend, it may be at a different rate. Your broker should be running both scenarios against your classification portfolio right now.

Lock in capacity with carriers who understand the corridor. The cross-border carriers who know the Detroit-Windsor crossings, who have FAST/C-TPAT enrollment, and who can navigate the multi-regime classification landscape are going to be in high demand through July and beyond. If you’re shopping for cross-border capacity on price alone, you’re making a mistake that shows up in border delays, misclassified entries, and duty exposure you didn’t plan for.

Bottom Line

The next 90 days are going to determine the cost structure of cross-border automotive freight for the next decade. The Supreme Court ruling reshuffled the legal deck. Section 122 is a stopgap with an expiration date. And the USMCA review will either confirm or rewrite the rules that every auto part crossing Detroit-Windsor has been priced against since 2020.

This is not a wait-and-see situation. The shippers who model the scenarios, audit their entries, and lock in corridor-specific logistics partners before July are going to come out of this with a cost advantage. Everyone else is going to spend the back half of 2026 reacting to changes they should have planned for.

If you need help running the numbers for your specific lanes, the contact form is at the bottom of every page on this site. This is exactly the kind of cross-border complexity we handle for our Detroit clients every day.