The American Party, known as the Native American Party before 1855 and colloquially referred to as the Know Nothing or the Know Nothing Party, was an Old Stock nativist political movement in the United States from the 1840s through the 1850s. Members of the movement were required to say "I know nothing" whenever they were asked about its specifics by outsiders, providing the group with its colloquial name.
Supporters of the Know Nothing movement believed that an alleged "Romanist" conspiracy to subvert civil and religious liberty in the U.S. was being hatched by Catholics. Therefore, they sought to politically organize native-born Protestants in defense of their traditional religious and political values. The Know Nothing movement is remembered for this theme because Protestants feared that Catholic priests and bishops would control a large bloc of voters. In most places, the ideology and influence of the Know Nothing movement lasted only one or two years before it disintegrated due to weak and inexperienced local leaders, a lack of publicly proclaimed national leaders, and a deep split over the issue of slavery. In parts of the South, the party did not emphasize anti-Catholicism as frequently as it emphasized it in the North and it stressed a neutral position on slavery, but it became the main alternative to the dominant Democratic Party.
