Aluminum tariffs (Section 232)

On March 8, 2018, alongside the steel tariff, President Trump imposed a 10% tariff on aluminum imports under Section 232 of the Trade Expansion Act, again citing a Commerce Department national-security finding. Aluminum is the metal in everything from beer cans to airplane frames and electrical wiring, so the reasoning was the same as for steel: a shrinking domestic smelting base is a defense problem.

The aluminum tariff followed the same exemption-then-no-exemption arc as steel — temporary carve-outs for Canada, Mexico and the EU, all of which lapsed on June 1, 2018. Canada, not China, was and remains the largest source of U.S. aluminum imports, which is why the tariff drew particular pushback from aluminum buyers.

Like steel, this tariff outlived the IEEPA era. Because it rests on Section 232 — a statute Congress explicitly wrote to authorize national-security trade restrictions — it was untouched by the Supreme Court's February 2026 ruling that struck down the IEEPA-based 2025 tariffs. The second Trump administration raised it to a flat 25% effective March 12, 2025, eliminating the original 10%/25% steel-aluminum asymmetry.

In plain terms: aluminum inputs in the U.S. have been more expensive since 2018, and materially more expensive since 2025.

Directly: U.S. companies that import aluminum (mill products, ingot, sheet, foil)

Ultimately: Downstream manufacturers (packaging, autos, aerospace, construction) and consumers, via higher input costs

Canada supplies roughly half of U.S. primary aluminum imports, so a large share of the tariff burden falls on a close ally rather than on the overcapacity the policy was nominally meant to address.

Downstream aluminum-consuming industries bore billions in added costs; estimates vary widely by methodology and year

The relative rarity of credible bottom-up estimates reflects how dispersed aluminum use is across the economy.

Source: Tax Foundation — Trump tariffs analysis