Examples of tariffs stretch from Britain’s Corn Laws in 1815 to the reciprocal duties the United States imposed on nearly every trading partner in April 2025. A tariff is a tax a government charges on goods crossing its border, and each real-world case shows a different reason a government reaches for the tool: protecting a domestic industry, punishing unfair trade practices, raising revenue, gaining leverage, or, most recently, pricing carbon at the border.
How a Tariff Is Calculated
The dollar cost of a tariff depends on how the rate is written. A specific tariff is a flat amount per unit: $20 per imported bicycle, whether the bike costs $100 or $1,000. An ad valorem tariff is a percentage of declared value, so a 10% duty on a $1,000 shipment costs $100. This is the most common form in modern trade. A compound tariff combines both, charging a fixed amount per unit plus a percentage of value.
Tariffs also split by purpose. A protective tariff is set high enough to make imports more expensive than local goods, shielding domestic producers. A revenue tariff exists mainly to raise money, often on goods the country doesn’t make itself. Most of the examples below are protective, because those are the ones that reshape entire industries.
The British Corn Laws (1815–1846)
Britain’s Parliament passed the Corn Laws in 1815 to protect domestic landowners and farmers, placing steep import duties on cereal grains including wheat, barley, and oats. The duties made foreign grain unaffordable even when domestic supplies ran short.1The National Archives. The Corn Laws Bread stayed expensive for decades, enriching landowners while urban workers spent much of their wages just to eat.
The laws fell in 1846, after the failure of the Irish potato crop made cheap imported grain a matter of survival. Prime Minister Robert Peel pushed repeal through over fierce opposition from his own Conservative party.2Encyclopedia Britannica. Corn Law The episode is the classic warning about what happens when a tariff protects a politically powerful minority at the broader public’s expense.
The Smoot-Hawley Tariff Act (1930)
The most infamous American tariff was signed on June 17, 1930, during the early months of the Great Depression. Smoot-Hawley raised import duties on thousands of goods by roughly 20%, originally to shield American farmers from falling crop prices.3United States Senate. The Senate Passes the Smoot-Hawley Tariff Congress expanded the bill well past agriculture, and industrial products were covered by the time it passed.
Retaliation was immediate. About two dozen countries raised duties on American exports within two years, and international trade fell by an estimated 65% between 1929 and 1934.4Encyclopaedia Britannica. Smoot-Hawley Tariff Act Smoot-Hawley didn’t cause the Depression, but it deepened it by choking off the trade that might have helped economies recover.
The 2025 Reciprocal Tariffs
On April 2, 2025, the President signed an executive order imposing an additional 10% ad valorem duty on all imports from every trading partner, effective April 5. Higher country-specific rates were scheduled to begin April 9 for dozens of countries listed in the order’s annex.5The White House. Regulating Imports with a Reciprocal Tariff to Rectify Trade Practices That Contribute to Large and Persistent Annual United States Goods Trade Deficits The stated goal was to match the tariff and non-tariff barriers other countries impose on American goods.
The same day the higher rates were set to begin, a follow-up order paused them for 90 days, dropping most countries back to the 10% baseline. China was the explicit exception. The reciprocal rate on Chinese goods climbed to 125%, stacking on top of existing Section 301 and other duties to push the total well above 145%.6The White House. Modifying Reciprocal Tariff Rates to Reflect Trading Partner Retaliation and Alignment In May 2025, the US and China reached a temporary agreement that cut the combined US levy on Chinese goods to roughly 30% for a 90-day window, while China dropped its retaliatory duties on American goods to 10%.
In July 2025, the pause on higher rates for other trading partners was extended, keeping the baseline at 10% for most countries.7The White House. Extending the Modification of the Reciprocal Tariff Rates The reciprocal episode shows how quickly tariffs escalate when countries retaliate in sequence, and how temporary pauses and bilateral deals create constant uncertainty for importers.
Steel and Aluminum Under Section 232
Section 232 of the Trade Expansion Act of 1962 lets the President adjust imports the Department of Commerce determines threaten national security.8Office of the Law Revision Counsel. 19 US Code 1862 – Safeguarding National Security In March 2018, the President used this authority to impose a 25% duty on steel imports and a 10% duty on aluminum imports from most countries, aimed at reviving domestic capacity that global overcapacity, particularly from China, had undercut.
In June 2025, those rates doubled to 50% ad valorem on both steel and aluminum from nearly all countries. The same 50% rate now applies to the steel and aluminum content of hundreds of downstream products, including wind turbines, mobile cranes, and railcars.9The White House. Adjusting Imports of Aluminum and Steel into the United States Extending the duty to downstream goods was a response to manufacturers dodging steel tariffs by importing semi-finished products already shaped or welded abroad.
Section 301 Tariffs on Chinese Goods
Section 301 of the Trade Act of 1974 lets the US Trade Representative impose tariffs in response to unfair trade practices such as intellectual property theft and forced technology transfer.10Office of the Law Revision Counsel. 19 US Code 2411 – Actions by United States Trade Representative The first round on Chinese goods took effect in 2018, covering industrial components and electronics at rates between 7.5% and 25%.11Federal Register. Notice of Action Pursuant to Section 301 – Chinas Acts, Policies, and Practices Related to Technology Transfer, Intellectual Property, and Innovation
In September 2024, those tariffs were sharply increased on strategic products:
- Electric vehicles: 100%
- Solar cells and modules: 50%
- Semiconductors: 50% (effective 2025)
- Lithium-ion EV batteries: 25%
- Lithium-ion non-EV batteries: 25% (effective 2026)
- Steel and aluminum products: 25%
- Ship-to-shore cranes: 25%
These are additional duties layered on top of normal tariff rates.12Federal Register. Notice of Modification – Chinas Acts, Policies and Practices Related to Technology Transfer A Chinese-made electric vehicle, for instance, faces the 100% Section 301 duty plus whatever reciprocal tariff is in effect, which is why so few Chinese EVs currently reach American consumers.
Anti-Dumping and Countervailing Duties
Not every tariff comes from a presidential proclamation. Anti-dumping and countervailing duties are trade remedies imposed after formal investigations by the Department of Commerce and the US International Trade Commission.13United States International Trade Commission. Trade Remedy Laws Administered by USITC
An anti-dumping duty targets a foreign company selling a product in the US below its production cost or below what it charges at home, and the duty is calculated to close that gap. A countervailing duty responds to foreign government subsidies that give exporters an artificial cost advantage. Both aim to level the playing field rather than protect an industry or raise revenue in the usual sense.14Enforcement and Compliance. An Introduction to US Trade Remedies
The two remedies often land on the same product at once, producing combined rates that dwarf typical tariffs. Certain Chinese steel products have drawn combined anti-dumping and countervailing duties exceeding 500%, reflecting findings of both heavy subsidies and pricing below production costs. Solar panels from multiple countries have faced similar layered duties. Each set is product-specific and country-specific, and rates are recalculated through annual reviews.
Export Duties
Most tariff talk focuses on imports, but some countries also tax goods leaving their borders. The US Constitution flatly prohibits this: “No Tax or Duty shall be laid on Articles exported from any State.”15Constitution Annotated. ArtI.S9.C5.1 Export Clause and Taxes Other governments face no such constraint.
China has long applied export duties and restrictions on rare earth elements, the minerals essential to EV batteries, wind turbines, and military equipment. Taxing or restricting exports lowers the domestic price of those inputs, giving Chinese manufacturers a built-in advantage over competitors in the US, Europe, and Japan. In April 2025, China tightened rare earth export controls further as a direct countermeasure to American tariffs. The strategy works because China dominates global rare earth mining and processing, leaving importers with few alternatives.
Developing countries with significant natural resources also use export duties as a straightforward revenue source and as an incentive to process raw materials at home. Duties on timber, agricultural commodities, and unprocessed minerals push manufacturers to build refining and processing capacity domestically rather than ship raw goods abroad.
The EU Carbon Border Adjustment Mechanism
The newest international example comes from Europe. On January 1, 2026, the EU’s Carbon Border Adjustment Mechanism entered its definitive phase.16European Commission. Carbon Border Adjustment Mechanism CBAM functions as an environmental tariff: EU importers of carbon-intensive goods like steel, cement, aluminum, fertilizers, and electricity must buy certificates based on the carbon emissions embedded in those products. The certificate price tracks the EU’s internal carbon trading market, so importers pay the same carbon cost European producers already face.
If an exporting country already charges its own carbon price, the importer can deduct that amount. The mechanism is designed to prevent “carbon leakage,” where manufacturers relocate to countries with looser environmental rules and then ship back into Europe. CBAM is a new category of tariff: one calibrated not to trade balances or national security, but to climate policy.
The End of Duty-Free De Minimis Shipments
For years, the most consumer-visible piece of US tariff policy was the de minimis rule. Under 19 USC 1321, shipments valued at $800 or less could enter the country without duties or formal customs processing.17Office of the Law Revision Counsel. 19 US Code 1321 – Administrative Exemptions This fueled direct-to-consumer e-commerce from overseas, particularly Chinese platforms that shipped low-cost parcels individually to sidestep duties.
On July 30, 2025, the President signed an executive order suspending the duty-free de minimis benefit for shipments from all countries, effective August 29, 2025.18The White House. Suspending Duty-Free De Minimis Treatment for All Countries The $800 threshold still exists in the statute, but the tax benefit no longer applies. Every imported package, regardless of value or origin, now faces applicable tariffs, taxes, and fees. For anyone who routinely ordered inexpensive goods from overseas, the change means higher prices and slower processing at the border.