Since the 1930s when the government began active regulation, US agriculture has undergone a revolution in productivity. Sally Clarke explains how government activity, from support for research to price supports and farm credit programs, created a climate favorable to rapid gains in productivity. Farmers in the Corn Belt delayed purchases of the tractor, the most important agricultural technology, despite the cost savings it promised. Tractor purchases required large sums of cash at a time when families faced unstable prices and unattractive credit markets. The New Deal inadvertently changed this investment climate. Regulation stabilized prices, introduced new sources of credit, and caused tool manufacturers and private creditors to revise their business strategies. Competitive farmers took advantage of these new conditions to invest in expensive technology and achieve new gains in productivity.