(Pictured left: A photo from a 1921 encyclopedia shows a tractor ploughing an alfalfa field)
Agriculture is a major industry in the United States and the country is a net exporter of food. As of the last census of agriculture in 2007, there were 2.2 million farms, covering an area of 922 million acres (3,730,000 km2), an average of 418 acres (1.69 km2) per farm. Agriculture in the United States is primarily governed by periodically renewed U.S. farm bills. Governance is both a federal and a local responsibility with the United States Department of Agriculture being the federal department responsible. Government aid includes research into crop types and regional suitability as well as many kinds of subsidies, some price supports and loan programs. U.S. farmers are not subject to production quotas and some laws are different for farms compared to other workplaces. A large part of the U.S. farm workforce is made up of migrant and seasonal workers, many of them recent immigrants from Latin America or aliens working under work permits. Additional laws apply to these workers and their housing which is often provided by the farmer.
Corn, turkeys, tomatoes, potatoes, peanuts, and sunflower seeds constitute some of the major holdovers from the agricultural endowment of the Americas. European agricultural practices greatly affected the New England landscape, leaving behind many physical foot prints. Colonists brought livestock over from Europe which caused many changes to the land. Grazing animals required a lot of land and food to sustain them and due to grazing, native grasses were destroyed and European species began to replace them. New species of weeds were introduced and began to thrive as they were capable of withstanding the grazing of animals, whereas native species could not. In 2004, of the 145 million employed workers in the US, 834,000 of them held jobs as agricultural workers. 83% of these jobs were as farm workers. The median hourly income as of May 2004 was $7.70 for farmworkers planting, growing and harvesting crops, and $8.31 for farmworkers tending to animals.