Abstract: The subject of this article is the role of a populist party in changing the two-party system in the state of Kansas, USA at the turn of the 19th - 20th centuries. The author examines the process of transforming the state party system and the attempts by populists to create a multi-party system in Kansas, where for several decades had dominated the Republican Party, which competed with the Democrats and defeated them in all local and national elections. This is the reason why the local populist party set before itself the main task of breaking the Republican domination and of luring to its side the electorate of the two main parties. As part of this study, the author applied the interdisciplinary approach, which allowed the author to more objectively evaluate all the factual material using the methodology of various social sciences and the Humanities. The author also widely used quantitative methods to count the electorate of various parties. This work is the first study in Russian historiography which demonstrates, on the basis of archival and published sources, the causes and consequences of the party struggle in 1888 - 1896 in Kansas. In the article's conclusion, the author concludes that the populist party was able to change the state party system only for a while, being unable to maintain its position in the long term.