When the last great North American frontier, the Great Plains, closed three decades into the twentieth century, farmers could no longer replace the exhausted soils on their farms with fertile, uncultivated lands elsewhere. The closing of the frontier caged American farmers. The fall in the prices of agricultural products after World War I, coupled with widespread soil exhaustion, deepened rural poverty during the 1920s. The Depression impoverished rural peoples even further, and it discredited the capitalist class. In a political-economic sense, the Depression leveled some elements of inequality. The Dust Storms of the mid-1930s provided graphic, visual evidence of environmental degradation on farms, and they focused popular attention on the need for more sustainable practices. Franklin D. Roosevelt responded, with support from the large New Deal coalition, pushing through reforms in soil conservation and forest restoration that have shaped natural resource practices in the United States for almost a century.