When did the third party start?

The concept of third parties in U.S. politics began in the late 19th century, with the emergence of groups like the Populist Party in the 1890s. However, the first significant third party was the Anti-Masonic Party, founded in 1828. Over time, various third parties have appeared, often addressing specific issues or representing diverse constituencies, but they have typically struggled to achieve lasting political power against the dominant Democratic and Republican parties.