History: The Great Depression, 1939-1943, United States

Even after the Wall Street Crash of 1929, optimism persisted for some time; John D. Rockefeller said that "These are days when many are discouraged. In the 93 years of my life, depressions have come and gone. Prosperity has always returned and will again." The stock market turned upward in early 1930, returning to early 1929 levels by April. This was still almost 30% below the peak of September 1929.
Together, government and business spent more in the first half of 1930 than in the corresponding period of the previous year. On the other hand, consumers, many of whom had suffered severe losses in the stock market the previous year, cut back their expenditures by ten percent. Likewise, beginning in mid-1930, a severe drought ravaged the agricultural heartland of the USA.
By mid-1930, interest rates had dropped to low levels, but expected deflation and the continuing reluctance of people to borrow meant that consumer spending and investment were depressed. By May 1930, automobile sales had declined to below the levels of 1928. Prices in general began to decline, although wages held steady in 1930; but then a deflationary spiral started in 1931. Conditions were worse in farming areas, where commodity prices plunged, and in mining and logging areas, where unemployment was high and there were few other jobs.
The decline in the US economy was the factor that pulled down most other countries at first, then internal weaknesses or strengths in each country made conditions worse or better. Frantic attempts to shore up the economies of individual nations through protectionist policies, such as the 1930 U.S. Smoot–Hawley Tariff Act and retaliatory tariffs in other countries, exacerbated the collapse in global trade. By late 1930, a steady decline in the world economy had set in, which did not reach bottom until 1933.