The domestic slave trade, also known as the Second Middle Passage and the interregional slave trade, was the term for the domestic trade of slaves within the United States that reallocated slaves across states during the antebellum period. It was most significant in the early to mid-19th century, when historians estimate one million slaves were taken in a forced migration from the Upper South: Maryland, Delaware, Virginia, Tennessee, Kentucky, North Carolina, South Carolina, and the District of Columbia, to the territories and newly admitted states of the Deep South and the West Territories: Georgia, Alabama, Florida, Louisiana, Mississippi, Arkansas, and Texas.