The PRI, or Institutional Revolutionary Party, was a political party in Mexico that dominated the country's political landscape for most of the 20th century, especially during the interwar period. Founded in 1929, the PRI was key in promoting a mix of nationalism, economic stability, and social reforms, which were critical as Mexico navigated the challenges of post-revolutionary reconstruction and economic recovery after World War I. The party's policies aimed to integrate various social groups and maintain political control through a system of patronage and electoral manipulation.