4 mars 1929 - Formation of the Institutional Revolutionary Party (PRI)

Description:

The PRI was formed by Plutarco Elías Calles mainly to contain the struggles for power within the revolutionary factions. Through manipulation and his leadership of the dominant PRI, Calles was able to control most of the Mexican government by 1934, even after his presidency ended.

Sources:
http://countrystudies.us/mexico/84.htm