In the United States, Southern cotton provided capital for the continuing development of the North. The cotton was largely produced through the labor of enslaved African Americans. It enriched both the Southern landowners and the Northern merchants. Much of the Southern cotton was trans-shipped through northern ports. In this era the slogan "Cotton is king" characterized the attitude of the South toward this monocrop.
Cotton remained a key crop in the Southern economy after emancipation and the end of the Civil War in 1865. Across the South, sharecropping evolved, in which landless black and white farmers worked land owned by others in return for a share of the profits. Some farmers rented the land and bore the production costs themselves. Until mechanical cotton pickers were developed, cotton farmers needed additional labor to hand-pick cotton. Picking cotton was a source of income for families across the South. Rural and small town school systems had split vacations so children could work in the fields during "cotton-picking."
It was not until the 1950s that reliable harvesting machinery was introduced.During the first half of the 20th century, employment in the cotton industry fell, as machines began to replace laborers and the South's rural labor force dwindled during the World Wars.
Cotton remains a major export of the southern United States, and a majority of the world's annual cotton crop is of the long-staple American variety.