Farm productivity yields: Crop Quick Stats, National Agricultural Statistics Service, U.S. Department of Agriculture.
Cost of firing workers: “You’re Fired: What It Costs to Sack a Worker,” The Economist, September 16, 2008.
U.S. Trade balance: U.S. Department of Commerce.
American attitudes on environment and economic growth: “Who Cares? Don’t Count on Public Opinion to Support Mitigation,” The Economist, December 3, 2009.