Tariffs in United States history have played different roles in trade policy, political debates and the nation's economic history

Economic history of the United States

The economic history of the United States has its roots in European colonization in the 16th, 17th, and 18th centuries. Marginal colonial economies grew into 13 small, independent farming economies, which joined together in 1776 to form the United States of America...

. Tariffs were the largest source of federal revenue from the 1790s to the eve of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, until it was surpassed by income taxes. Tariffs are taxes on imports and are collected before the shipment can be unloaded at a U.S. port; the collected money is called customs

Customs

Customs is an authority or agency in a country responsible for collecting and safeguarding customs duties and for controlling the flow of goods including animals, transports, personal effects and hazardous items in and out of a country...

 or custom duties.

The other major source of Federal tax income was excise taxes which have fluctuated from minor to major sources of tax income.