The enslavement of black people in the United States lasted for more than two centuries and created a complex legal, economic, and social infrastructure that can still be seen today. When Congress outlawed the Transatlantic Slave Trade beginning in 1808, new demand for slaves had to be met by natural reproduction in the local slave population or by domestic trade. As a result of the increased demand for slave labor due to the booming cotton industry, an estimated one million slaves were forcibly transferred from the Upper South to the Lower South between 1810 and 1860.
Beginning in the 19th century, the introduction of new methods of transportation altered the routes used by slave traders. The arrival of the steamboat in 1811 allowed traders to send enslaved people from markets along the Ohio and Mississippi rivers to Natchez, Mississippi, and New Orleans, Louisiana. The steam locomotive arrived in the 1830s and by the 1840s and 1850s, rail lines stretched across the South, becoming the preferred method for transporting slaves to the Lower South. Trips that took weeks by foot now took less than two days by rail.
The domestic slave trade brought economic benefits to the entire South. Slave traders accumulated substantial wealth by purchasing slaves in the Upper South and transporting them to the Lower South. It is estimated that more than half of all slaves in the Upper South were separated from a parent or child, and a third of their marriages were destroyed by forced migration. This clearly exploitative treatment of enslaved people challenged the benign slavery myth by calling into question how slavery benefitted the enslaved.