The main causes of the Great Depression in the United States included the stock market crash of 1929, widespread bank failures, and declining consumer and business confidence. The crash triggered massive unemployment, as businesses cut back or closed, leading to a spiral of reduced consumer spending. Additionally, the agricultural collapse, exacerbated by drought conditions in the Midwest, worsened economic hardship for farmers. Poor monetary policy and inadequate government responses further deepened the crisis. The Great Depression had profound and lasting effects on American society and led to significant economic reforms during the New Deal era aimed at preventing future economic disasters.