 This period has been marked by changes in policy and amendments to the 1917 Mexican Constitution to allow for neoliberal economic policies.Following the formation in 1929 of the precursor to the Partido Revolucionario Institucional (PRI), this party controlled most national and state politics after 1929, and nationalized the oil industry in the 1930s.During World War II, Mexico was a strong ally of the United States, and benefited significantly by supplying metals to build war material as well as guest farm workers, who freed US American men to fight overseas.