Why were tariffs first supported, then opposed, by American companies in the period after the Civil War?

Explanation:

The goal of the North was to keep the South in the Union. ... This is from an encyclopedia entry: “The tensions which developed between the South and the North over the tariff policy contributed materially to the outbreak of the Civil War. The business interests in the South favored lower tariffs or free trade with Europe.

Why did the United States use protective tariffs during the antebellum period?

Their purpose was to generate revenue for the federal government and to allow for import substitution industrialization (industrialization of a nation by replacing foreign imports with domestic production) by acting as a protective barrier around infant industries.

Why did American business owners favored high tariffs on foreign goods?

The American System included high tariffs (taxes) on imported goods, intended to force Americans to buy products from the Northern State's factories. 2. This made Southerners feel that the American System was making Northern States (which manufacture, rather than grow food) RICH.