After the United States' Louisiana Purchase of 1803, migration into the territory increased from the US. Natchitoches grew along with the population in the parish. Initially, the Americans were primarily of English and Scots-Irish ancestry and of Protestant faith. They developed several cotton plantations along the Red River. Numerous enslaved African Americans were brought to the area through the domestic slave trade to work the cotton, and provide all other skills on these plantations, generating the revenues for the wealthy planters before the Civil War.