Another striking change occurring in the agricultural sector during the past century involves farm labor and population. Farm labor requirements declined steadily due to mechanization, economic conditions, and the western expansion of agriculture coming to an end.

The increased use of machines to perform work formerly done by humans and then by animals raised farm efficiency while reducing the need for farm labor. The Great Depression left many farm laborers unemployed until the economic boom during World War II created employment opportunities in urban centers and led to a large migration from rural areas. The change in emphasis from development of new agricultural land to more intensive farming on existing land also contributed to lower demand for agricultural labor.