This dataset provides estimates for the corn and soybean biomass used for biofuel production (corn ethanol and soybean biodiesel, respectively) based on the geographic locations of biofuel plants provided by US Energy Information Administration for the 2017 USDA crop census data. County-level biomass was allocated to each biofuel plant based on distance to the plant assuming all biomass is located at each county’s centroid. If two plants were competing for the same county’s biomass, priority was given to the biofuel plant with the highest production capacity. County-level biomass estimation was validated using reported state-level biomass to biofuel values. Reported values could only be found for 11 states, but the mean difference between reported and estimated biomass used for biofuel production was 1.4% for corn ethanol.