We explicitly measure corn acreage response to the biofuels boom from 2006 to 2010. Specifically, we use newly available micro-scale planting data over time to test whether corn cultivation intensifies in proportion to the proximity of ethanol processors. We control for the endogeneity of plant location to corn acreage by using transportation network data for instruments. Our results show that reducing the distance between a farm and an ethanol plant by one percent increases acreage in corn by 0.64% and reveal a price elasticity of supply of 0.47%. To our knowledge, this is the first study that measures changes in location and intensity of corn planting in response to incentives posed by the recent biofuels boom. The results can serve as a springboard for researchers and policy-makers concerned with crop diversity, environmental sustainability, and greenhouse gas emissions.