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.
Customs duties in the United States
Customs duty rates may be expressed as a percentage of value or dollars and cents per unit. Rates based on value vary from zero to 20% in the 2011 schedule. Rates may be based on relevant units for the particular type of goods (per ton, per kilogram, per square meter, etc.). Some duties are based in part on value and in part on quantity. The United States applies a Customs tariff that is among the lowest in the world: 3% on average.