1800s, the United States was largely agricultural, with more than 80 percent of the population engaged in farming. Most of the manufacturing centered on the first stages of the transformation of raw materials, with lumber and sawmills, textiles, and boots and shoes leading the way. The rich resource endowments contributed to the rapid economic expansion of the nineteenth century. Ample land availability allowed the number of farmers to keep growing, but activity in manufacturing, services, transportation, and other sectors grew at a much faster pace. Thus, by 1860, the share of the rural population in the U.S. had fallen from over 80 percent to roughly 50 percent. In the 19th century, recessions frequently coincided with financial crises. The 1837 Panic was followed by a five-year depression marked by bank failures and then-record-high unemployment levels. Because of the great changes in the economy over the centuries, it is difficult to compare the severity of modern recessions to early recessions. Recessions after World War II appear to have been less severe than earlier recessions, but the reasons for this are unclear. 20th century At the beginning of the century, new innovations and improvements in existing innovations opened the door for improvements in the standard of living among American consumers. Many firms grew large by taking advantage of economies of scale and better communication to run nationwide operations. Concentration in these industries raised fears of monopolies that would drive prices higher and output lower, but many of these firms were cutting costs so fast that trends were towards lower prices and more output in these industries. Many workers shared the success of these large firms, which typically offered the highest wages in the world. The United States has been the world's largest national economy in terms of GDP since at least the 1920s. For many years following the Great Depression of the 1930s, when the danger of recession appeared most serious, the government strengthened the economy by spending heavily itself or cutting taxes so that consumers would spend more and by fostering rapid growth in the money supply, which also encouraged more spending. Ideas about the best tools for stabilizing the economy changed substantially between the 1930s and the 1980s. From the New Deal era that began in 1933 to the Great Society initiatives of the 1960s, national policymakers relied principally on fiscal policy to influence the economy. During the world wars of