What was one reason for the growth of the domestic slave trade? A. The need for labor declined in the North. B. Northern plantations had too many slaves C. Slaves in the Old South did not run away. D. The international slave trade ended.

 D. The international slave trade ended.

One reason for the growth of the domestic slave trade in the United States was D. The international slave trade ended.

The international slave trade, which involved the importation of enslaved individuals from Africa, was prohibited in the United States after the Atlantic slave trade was banned in 1808. With the end of the international slave trade the demand for labor in the South continued to grow due to the expansion of cotton plantations and other agricultural enterprises. As a result, slaveholders in the Upper South, where tobacco cultivation was declining, began selling their surplus slaves to the Deep South, where cotton production was rapidly expanding. This internal trade in slaves within the United States became known as the domestic slave trade, leading to the forced migration of thousands of enslaved people from the Upper South to the Lower South during the early to mid-19th century.