The Agriculture Department oversees the food and farm system in the United States, from inspecting meat, poultry, and egg products for safety to administering crop insurance and subsidy programs that support farmers against price swings and weather disasters. It also manages the nation's 154 national forests and 20 national grasslands, covering nearly 200 million acres.

USDA runs the country's largest nutrition assistance programs, including the Supplemental Nutrition Assistance Program (SNAP, formerly food stamps) and the National School Lunch Program, which together account for the majority of the department's total budget, since these programs are legally mandatory rather than subject to annual discretionary funding fights.

The department also funds rural development, including rural housing, utility, and business loan programs, conducts agricultural research through its Agricultural Research Service, and publishes closely watched economic data, including crop production forecasts that move commodity markets worldwide.