Charleston, South Carolina:

By 1840, the Market Hall and Sheds, where fresh meat and produce were brought daily, became a hub of commercial activity. The slave trade also depended on the port of Charleston, where ships could be unloaded and the slaves bought and sold. The legal importation of African slaves had ended in 1808, although smuggling was significant. However, the domestic trade was booming. More than one million slaves were transported from the Upper South to the Deep South in the antebellum years, as cotton plantations were widely developed through what became known as the Black Belt. Many slaves were transported in the coastwise slave trade, with slave ships stopping at ports such as Charleston.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". In what era did one million slaves get trade throughout the South?
in the antebellum years