<P> The Mexican Revolution started in 1911 ; it alarmed American business interests that had invested in Mexican mines and railways . The United States involvement in the Mexican Revolution , include , among other violations of sovereignty , the ambassadorial backing of a coup and assassination of President Francisco I. Madero and the military occupation of Veracruz . Large numbers of Mexicans fled the war - torn revolution into the southwestern United States . Meanwhile , the United States increasingly replaced Britain as the major trade partner and financier throughout Latin America . The US adopted a `` Good Neighbor Policy '' in the 1930s , which meant friendly trade relations would continue regardless of political conditions or dictatorships . United States signed up the major countries as allies against Germany and Japan in World War II . However , some countries like Argentina , Chile , Ecuador , Paraguay , Uruguay and Venezuela only joined the Allied side in 1945 . The era of the Good Neighbor Policy ended with the ramp - up of the Cold War in 1945 , as the United States felt there was a greater need to protect the western hemisphere from Soviet Union influence and a potential rise of communism . These changes conflicted with the Good Neighbor Policy 's fundamental principle of non-intervention and led to a new wave of US involvement in Latin American affairs . </P>
american continued interest in latin america came from an earlier policy known as
Good Neighbor Policy