For most of its history, the United States has had a two-party system. From the Federalists and Anti-Federalists, to the modern-day Democrats and Republicans, there are usually always two political parties that dominate the U.S. government at any one time.

Since the 1820s, the United States has also had a plethora of third parties that challenge the two-party system. Though these parties rarely gain much national power, many have had a significant impact on U.S. political and party dynamics. This was the case with the very first third party, the Anti-Masonic Party, which was founded on the conspiracy theory that an elite group of Freemasons were secretly controlling the U.S. government.

The Freemasons were a popular fraternal order during the colonial era, and prominent founding fathers such as Benjamin Franklin and George Washington were involved in Freemason societies. These societies supposedly evolved from actual masonry guilds; yet by the 18th century, Freemason societies had become social clubs for elite white men in Europe and the 13 Colonies.

Freemasonry continued to grow in the United States during the first two decades of the 19th century, in part because it was a good way for people who wanted to enter politics to network, says Mark Schmeller, a history professor at Syracuse University.

“It’s a way for professional men, newspaper editors and politicians to kind of get to know one another,” he says. “So, if you’re embarking on a political career, it’s a pretty good idea to join a Masonic lodge.” Notable members during the 1820s included Henry Clay, who became secretary of State in 1825, and Andrew Jackson, who became president in 1829.

The Freemasons’ secret initiation ceremonies, which outsiders weren’t supposed to know about, helped foster suspicions about the group. In 1826, a stoneworker named William Morgan alleged that he was planning to publish an exposé on the Freemasons. His subsequent disappearance that year, and rumors that Freemasons had murdered him to prevent his exposé, was a catalyst among people who were already suspicious of the order. Some suspected the Freemasons might even be trying to destroy the U.S. republic, the institution of Christianity or both.

Around 1828, a group of men in New York who opposed Freemasonry as well as the emerging Jacksonian Democratic Party that dominated the state created a new party: the Anti-Masonic Party. Because it never gained the same national following as the two main parties of the day—the Jacksonian Democrats and the National Republicans (who became the Whigs in 1833)—historians consider it to be America’s first third party.

The idea that Freemasons were secretly running the government—and maybe trying to destroy it—may have seemed convincing at the time given that so many political elites actually were in Freemason societies. Conspiracy theories “don’t have to be completely wrong,” says Andrew Burt, author of American Hysteria: The Untold Story of Mass Political Extremism in the United States. “And actually it’s the half-truth that makes them so dangerous.”

As such, the Anti-Masonic Party attracted a lot of members who went on to become prominent politicians over the next few decades. These included William H. Seward, who would later be Abraham Lincoln’s secretary of State; Thaddeus Stephens, who became an influential abolitionist in the House of Representatives; and Millard Fillmore, who became president in 1850.

Even though the party remained small, it fueled a rising anti-Masonic sentiment, and led to the closing of many Freemason societies. Some churches threatened to kick out parishioners unless they quit the Freemasons. When President John Quincy Adams was running for reelection in 1828, he found it necessary to declare: “I am not, never was, and never shall be a Freemason.” After losing the election, Adams even joined the Anti-Masonic Party for a period of time.

In addition to fueling opposition to Freemasonry, the Anti-Masonic Party’s theories about Freemasons contributed to the rise of conspiracy theories about other groups, says Mark Cheathem, a history professor at Cumberland University.

“During the 1830s, in particular, you have sort of a mixing of anti-Masonic conspiracy theories with anti-Catholic conspiracy theories with anti-Mormon conspiracy theories,” he says. These conspiracy theories portrayed Freemasons, Catholics and Mormons as “outside forces that are trying to manipulate the American people and the U.S. government for the benefit of the elite few.”

The third party’s influence extended to political operations in the major two parties. In 1831, the Anti-Masonic Party held the first national presidential nominating convention, a practice that the other parties soon adopted. The Anti-Masonic Party also helped spread its message through the use of party newspapers—a tactic that the main parties began to use as well.

Most people in the Anti-Masonic Party migrated over to the Whig Party in the 1830s, and by the end of the decade, the Anti-Masonic Party had basically disappeared. However, it established a precedent for small third parties that challenged the two-party system.

After the Anti-Masonic Party came the Know-Nothing Party, the Free Soil Party, the Socialist Party, the Bull Moose Party and many others. In 2022, the two largest third parties by voter registration are the Green Party and the Libertarian Party.