Know-Nothing Party

Know-Nothing Party, U.S. political party formed in the 1840s to exclude recently immigrated Roman Catholics from politics. The party sought to elect only native-born citizens to office and to require 25 years of residence for citizenship. It won success in the 1854 election as the American Party, but split irremediably in 1856 over the slavery issue. Its name came from its members' habit of saying they “knew nothing” of the movement.