According to Paul Bairoch, since the end of the 18th century, the United States has been "the homeland and bastion of modern protectionism". In fact, the United States never adhered to free trade until 1945. For the most part, the "Jeffersonians" strongly opposed it. In the 19th century, statesmen such as Senator Henry Clay continued Hamilton's themes within the Whig Party under the name "American System." The opposition Democratic Party contested several elections throughout the 1830s, 1840s, and 1850s in part over the issue of the tariff and protection of industry. In the U.S., the Democratic Party favored moderate tariffs used for government revenue only, while the Whigs favored higher protective tariffs to protect favored industries. The economist Henry Charles Carey became a leading proponent of the "American System" of economics. This mercantilist "American System" was opposed by the Democratic Party of Andrew Jackson, Martin Van Buren, John Tyler, James K. Polk, Franklin Pierce, and James Buchanan. The fledgling Republican Party led by Abraham Lincoln, who called himself a "Henry Clay tariff Whig", strongly opposed free trade and implemented a 44-percent tariff during the Civil War—in part to pay for railroad subsidies and for the war effort, and to protect favored industries.William McKinley  stated the stance of the Republican Party  as thus:
Question: Who opposed the mercantilist "American System?
Answer: Democratic Party