The Great Depression began in 1929 in the U.S. and was a worldwide economic downturn. It started with an overwhelming collapse of stock-market prices on the New York Stock Exchange. Perpetuated by policy errors, the Great Depression lasted until about 1939. Enacted by Congress to address some of the problems of the Great Depression, the Smoot-Hawley Act hiked tariffs on more than 20,000 imported goods and other countries quickly reciprocated. Some contend that Smoot-Hawley actually significantly compounded the impact of the crash. 
- About the Great Depression. UIUC.
- Financial crisis: Don't panic this is not the Great Depression. The Telegraph.