Tariff
In contrast, in economic theory tariffs are viewed as a primary element in international trade with the function of the tariff being to influence the flow of trade by lowering or raising the price of targeted goods to create what amounts to an artificial competitive advantage. When tariffs are viewed and used in this fashion, they are addressing the country's and the competitors' respective economic healths in terms of maximizing or minimizing revenue flow rather than in terms of the ability to generate and maintain a competitive advantage which is the source of the revenue. As a result, the impact of the tariffs on the economic health of the country are at best minimal but often are counter-productive.
History of taxation in the United States
Tariffs have played different roles in trade policy and the economic history of the United States. Tariffs were the largest source of federal revenue from the 1790s to the eve of World War I, until it was surpassed by income taxes. Since the revenue from the tariff was considered essential and easy to collect at the major ports, it was agreed the nation should have a tariff for revenue purposes.