Over the last twenty five years commodity crop farms have steadily declined in number and grown in average size, and production has shifted to larger operations. During the same period, the share of agricultural payments going to large farms has increased, in large part because payments are tied to actual or historical crop production. This study evaluates whether payments from federal farm programs may have contributed to the concentration of farmland. Using zip code-level data constructed from the micro files of the 1987-2002 Agriculture Censuses the study estimates the association between government payments per acre and subsequent growth in weighted median farmland area. A semi-parametric generalized additive model controls for location and initial concentration levels, and narrows comparisons to nearby zip codes with similar average farm sizes. Findings indicate, both with and without spatial controls, that government payments are strongly associated with subsequent concentration growth.