Tariff
A tariff is a tax on imports or exports between sovereign states. It is a form of regulation of foreign trade. It is a policy that taxes foreign products to encourage or protect domestic industry. It helps limit trade deficits. The tariff is historically used to protect infant industries and to allow import substitution industrialization.
Tariff in United States history
Tariffs have historically served a key role in the nation's foreign trade policy and as a source of federal income. Tariffs were the greatest (approaching 95% at times) source of federal revenue until the Federal income tax began after 1913. For well over a century the federal government was largely financed by tariffs averaging about 20% on foreign imports.