The U.S. Renewable Fuel Standard (RFS) requires blending increasing quantities of biofuels into the U.S. surface vehicle fuel supply. In 2013, the fraction of ethanol in the gasoline pool effectively reached 10%, the ethanol capacity of the dominant U.S. gasoline blend (the "E10 blend wall")....

Renewable fuel standards, low carbon fuel standards, and ethanol subsidies are popular policies to incentivize ethanol production and reduce emissions from transportation. Compared to carbon trading, these policies lead to large shifts in agricultural activity and unexpected social costs. We...