 His nephew, governor of Texas Manuel María de Salcedo, interpreted the order as allowing slaveholders from the United States to enter Texas to reclaim runaway slaves.The United States outlawed the importation of slaves in 1808, but domestic trade flourished, especially in New Orleans during the antebellum decades.In part due to the slave trade, New Orleans was the fourth largest city in the US in 1840 and one of the wealthiest.