The Anti-Masonic Party was the earliest third party in the United States. Formally a single-issue party, it strongly opposed Freemasonry in the United States. It was active from the late 1820s, especially in the Northeast, and later attempted to become a major party by expanding its platform to take positions on other issues. It declined quickly after 1832 as most members joined the new Whig Party; it dissolved after 1838.
The party was founded following the disappearance of William Morgan, a former Mason who had become a prominent critic of the Masonic organization. Many believed that Masons had murdered Morgan for speaking out against Masonry and subsequently many churches and other groups condemned Masonry. As many Masons were prominent businessmen and politicians, the backlash against the Masons was also a form of anti-elitism. The Anti-Masons purported that Masons posed a threat to American republicanism by secretly trying to control the government. Furthermore, there was a strong fear that Masonry was hostile to Christianity.