The American Party, better known as the Know Nothings, was an American nativist political party which was active from 1844 to 1860. The Know Nothings originated as a secret society founded in 1844 by Lewis Charles Levin, who believed that unrestricted immigration from Ireland and Germany would lead to a Catholic takeover of the United States and the destruction of the Protestant-majority American democracy due to "Papist" and "Romanist" influence over Catholic Americans. The Know Nothings took advantage of a growing hostility toward Catholic immigrants during the 1840s, and Levin was elected the USA's first Jewish congressman. The society gained its name from its secrecy, as, when questioned about the society, its members would say, "I know nothing." The Know Nothings, while right-wing in outlook, claimed to be supporting the country's classical liberal democracy, as they blamed Pope Pius IX for putting down the liberal Revolutions of 1848 in Europe, and claimed that the Pope would use the archbishops to influence Catholics into supporting tyranny and opposing material prosperity. In 1854, the Know Nothings swept the state of Massachusetts and won the mayorship of Philadelphia, and its membership rose from 50,000 to 1,000,000 as the result of the Whigs' dissolution and an influx of Democrats. In 1854, the Know Nothing spread to California, where a Know Nothing judge was able to prevent Chinese immigrants from testifying against whites in court. In 1855, Know Nothing Levi Boone was elected Mayor of Chicago, and he banned immigrants from holding city jobs. In Ohio, the Know Nothings even gained the support of several immigrants, namely the Protestant Scots-Irish immigrants and Lutheran Germans, who also had historical rivalries with Catholics. In the American South, former Whigs, discontented Democrats, and supporters of state aid joined the Know Nothings, but the movement began to collapse in the South after losing the Virginia gubernatorial election due to Democratic claims that the Know Nothings were allied to northern abolitionists.
After 1855, the party also declined in the North, as it had failed to take a stance on the slavery issue, and an influx of "Old Line" Whigs into the party's ranks led to the party's platform shifting from anti-foreignism to nationalism and opposition to sectionalism. In 1856, Know-Nothing presidential candidate Millard Fillmore carried Maryland with eight electoral votes and winning 23% of the nationwide popular vote. Know Nothing member Nathaniel Banks, who had inspired the party's growth, decided to leave the party for the Republicans with two-thirds of the Know Nothings' membership, as he was unwilling to strengthen his anti-immigrant views even further. After Dred Scott v. Sandford in 1857, most of the anti-slavery Know Nothings joined the Republicans, while their proslavery activists joined the Constitutional Union Party in 1860. In the 1860 presidential election, even after the Republican Party stated its opposition to changing its naturalization laws (in an attempt to pander to German Protestant immigrants), nativist voters were wooed by such former Know Nothing leaders as Daniel Ullman, who campaigned for the Republican Party in eastern Pennsylvania and New York City. In some areas Republican spokesmen appealed to nativist voters by attacking the Pope and Catholic Church, although they carefully avoided expressing hostility to all foreigners. Most nativists eventually cast their lot with the Republicans, even though it had made no concessions to them in its platform, and the Republican Party viewed their support as a distinct political liability in spite of the necessity of obtaining their votes. As anti-slavery supplanted nativism in the Republican program, the Protestant foreign vote began to shift away from the Democrats, with anti-slavery provind to be more popular than temperance and anti-foreignism. Nativism continued to be a widespread cultural impulse among Republicans, but it declined as a force in politics, with nativism becoming increasingly confined to Old Line Whigs who were much more concerned with nationalism than Know-Nothingism,
In New York City, under political boss William Cutting, a branch of the Know Nothings continued to run slates of nativist candidates in local elections until 1863, when Cutting was killed in battle with the rival Irish Catholic Dead Rabbits gang amidst the New York draft riots. His candidate for Sheriff, Richard Parrish, was defeated in a landslide by Tammany Hall-backed Democrat, and the party was no more.