It isn't easy to give a brief summary of the Great Depression. It was, without a doubt, the longest and most severe economic downturn in American history. Widely held to begin with the stock market crash of 1929, the Depression lasted until the advent of American involvement in World War II. Unemployment skyrocketed during the Depression years, reaching levels as high as one third of the population. Output shrank tremendously, falling by ten percent a year from 1929 to 1932. Nearly half of the commerical banks of the United States failed during the Depression. Crop prices fell by over fifty percent. People went hungry because so much food was produced that production became unprofitable. Others were unemployed because they had produced more than could be sold. Huge numbers of Americans had their lives upset by the Depression. Tens of thousands of migrant farm workers travelled the nation looking for employment. Homelessness, poverty and general despair characterized much of the nation.