Much of the history of 20th Century in Latin America has been characterized by political instability and turmoil. Nonetheless, some political trends may still be recognized. In Central America, oligarchic systems of governance prevailed at the end of the 19th Century. The first quarter of the 20th Century was maked by political unrest and multiple changes in government. And in the Caribbean, most islands were administered by European countries and the United States until well after World War II.
The collapse of the stock market in 1929 and the subsequent world wide economic crisis also had political effects throughout Central and South America, and as in Europe there were many regime changes including the installation of authoritarian systems. After WWII there was a move toward more democratic forms of governance and multi-party states. Colonies gained independence or were absorbed fully into the mother country.
The political atmosphere changed again in the 1960s when military and dictatorial regimes predominated. During the 1980s there was a shift toward more democratic systems with multi-party elections, and almost all colonies had become either self-governing or independent. The final frame shows that multi-party states predominate as the most common political regime at the turn of the 21st Century.
Historians today differ in their opinions about why this trend toward more democratic forms of political systems emerged in Latin America at the end of the 20th Century. Many believe that the explanation for this expansion of multi-party forms of governments is the result of the West emerging from the Cold War as the model for countries with higher levels of living standards and political stability. Others believe that rising global prosperity, the growing integration of world economies, and the increasing influence of the United States and Europe in South America have contributed to this growth of multi-party systems in the region. In contrast, Marxist historians would argue that these changes are superficial and that what we call a "multi-party" state is a euphemism for the traditional oligarchic state.