U.S. real GDP fell by about 29% from 1929 to 1933 during the Great Depression. The contraction was one of the deepest declines in modern American economic history and reflected collapsing consumption, investment, industrial output, and international trade.
The downturn began after the 1929 financial shock but was intensified by bank failures, falling prices, debt burdens, and restrictive policy choices. Industrial production and construction dropped especially sharply, while unemployment rose to roughly one-quarter of the labor force by 1933.
The figure refers to real gross domestic product, which adjusts for changing prices. That distinction matters because nominal GDP also fell, but inflation and deflation can change the appearance of an economy when output is measured only in current dollars.
The economy began recovering after 1933, although unemployment remained high for years. The Great Depression was international, but its timing and severity differed among countries.