What was the name of the 1930 US tariff act that raised import duties to record levels?

The 1930 U.S. tariff act that raised import duties to record levels was the Smoot–Hawley Tariff Act.

Its formal legal name was the Tariff Act of 1930, and President Herbert Hoover signed it on June 17, 1930. It is named for its principal congressional sponsors: Senator Reed Smoot of Utah, who chaired the Senate Finance Committee, and Representative Willis C. Hawley of Oregon, who chaired the House Ways and Means Committee.

The act raised tariffs on more than 20,000 imported goods, including agricultural and manufactured products. Supporters hoped higher duties would protect American farms and factories during the early Great Depression. Instead, trading partners retaliated with tariffs of their own, contributing to a sharp decline in U.S. exports and international trade.

The law is often blamed for causing the entire Great Depression, but that is too simple: the Depression had multiple causes, including financial collapse and deflation. Smoot–Hawley is better understood as a protectionist policy that worsened an already severe global downturn. It was followed by the more liberal Reciprocal Trade Agreements Act of 1934.