Political protest against immigrants has come to a head several times in American history. The most famous and influential such protest was exemplified by the Know-Nothing Party, founded in 1854 and directed especially against Catholic immigrants. By the end of 1855 the party had elected eight governors, over one hundred Congressmen, and thousands of local officials. Prominent politicians of every persuasion joined the party, which then changed its name to the American Party. It became a major element in the new Republican Party, which first produced a presidential candidate in 1856. The party and its influence has not attracted much attention from historians, because the events involved in the coming of the Civil War eclipsed interest in a movement that was only peripherally involved with Civil War issues.

The Know-Nothings had a precipitous decline, starting with the 1856 election, at which their presidential candidate Millard Fillmore carried only one state. The Republican Party soon eclipsed it, too. Tyler Anbinder has written the first comprehensive history of the Know-Nothings, and his book represents a major revision of historiography in the years leading up to the Civil War.