Tariff
A tariff is called an optimal tariff if it's set to maximize the welfare of the country imposing the tariff. It is a tariff derived by the intersection between the "trade indifference curve" of that country and the offer curve of another country. In this case, the welfare of the other country grows worse simultaneously, thus the policy is a kind of "beggar thy neighbor policy". If the offer curve of the other country is a line through the origin point, the original country is in the "condition of a small country", so any tariff worsens the welfare of the original country.
Tariff in United States history
During the Revolution, the British blockade from 1775 to 1783 largely ended foreign trade. In the 1783–89 Confederation Period, each state set up its own trade rules, often imposing tariffs or restrictions on neighboring states. The new Constitution, which went into effect in 1789, banned interstate tariffs or trade restrictions, as well as state taxes on exports.