The US swine industry has dramatically reorganized over the last two decades. Economic concentration in the slaughter sector has increased and hog production has consolidated economically and geographically. Increases in the geographic concentration of hog production have led to water pollution through spills and leakage from high numbers of very large manure storage lagoons centered within limited areas, such as a few counties. The global restructuring of agro-food systems has promoted the development of intensive and concentrated livestock production. However, national, state and local institutions, and dynamics have also influenced the structure of geographic concentration of hog production. Using state-level and national-level time series data from 1975 - 1996, we find that national-level increases in concentration in the hog-processing sector are positively associated with geographic concentration of production within states. However, we also find that state, and even local, government policy can mitigate, or worsen, the geographic concentration of hog production.