The 1930s (pronounced "nineteen-thirties" and commonly abbreviated as "the 30s") was a decade of the Gregorian calendar that began on January 1, 1930, and ended on December 31, 1939.
The decade was defined by a global economic and political crisis that culminated in the Second World War. It saw the collapse of the international financial system, beginning with the Wall Street Crash of 1929, the largest stock market crash in American history. The subsequent economic downfall, called the Great Depression, had traumatic social effects worldwide, leading to widespread poverty and unemployment, especially in the economic superpower of the United States and in Germany, which was already struggling with the payment of reparations for the First World War. The Dust Bowl in the United States (which led to the nickname the "Dirty Thirties") further emphasised the scarcity of wealth. U.S. President Franklin D. Roosevelt, elected in 1933, introduced a program of broad-scale social reforms and stimulus plans called the New Deal in response to the crisis.
In the wake of the Depression, the decade also saw the rapid retreat of liberal democracy as authoritarian regimes emerged in countries across Europe and South America, including Italy, Spain, and in particular the Third Reich in Nazi Germany. With the rise of Adolf Hitler, Germany undertook a series of annexations and aggressions against neighboring territories in Central Europe, and imposed a series of laws which discriminated against Jews and other ethnic minorities. Weaker states such as Ethiopia, China, and Poland were invaded by expansionist world powers, with the last of these attacks leading to the outbreak of World War II on September 1, 1939, despite calls from the League of Nations for worldwide peace. World War II helped end the Great Depression when governments spent money for the war effort. The 1930s also saw many important developments in science and a proliferation of new technologies, especially in the fields of intercontinental aviation, radio, and film.