A little thing called the US Constitution Article 1, Section 9 made selling slaves to foreign owners very problematic. Even among slave owners, the international slave trade was considered evil.
There were some states in which slaves represented roughly half the total population. Their birth rate was not anything remotely approaching twice the birthrate of Whites.
Well all those slaves had to come from somewhere. In 1810, two years after importation was shutdown, the slave population was a little more than 1 million nation wide. By 1860, the slave population had reached nearly 4 million, concentrated in basically 15 southern states. That’s a four times increase.
Article I, Section 9, Clause 1: The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person.
Read that more carefully. No it doesn't. This only cover the importation of slaves. It says nothing about export.
Well all those slaves had to come from somewhere. In 1810, two years after importation was shutdown, the slave population was a little more than 1 million nation wide. By 1860, the slave population had reached nearly 4 million, concentrated in basically 15 southern states. That’s a four times increase.
Have you done any genealogy research? The birth rate back then was tremendous. You'd be stunned by the number of families with 7, 8, 9 surviving kids. With a 26% population growth rate per decade, the population doubles every 30 years. That's roughly what the natural population growth rate was in the early 18th century.