From '20. and odd' to 10 million: the growth of the slave population in the United States

This research note describes the growth of the slave population in the United States and develops several new measures of its size and growth, including an estimate of the total number of slaves who ever lived in the United States. Estimates of the number of births and slave imports are provided in ten-year increments between 1619 and 1860 and in one-year increments between 1861 and 1865. The results highlight the importance of natural increase to the rapid growth of the U.S. slave population and indicate that approximately 10 million slaves lived in the United States, where they contributed 410 billion hours of labor. A concluding discussion highlights a few descriptive statistics historians might find useful, including the cumulative number of slaves who lived in the United States by decade and the proportion of slaves who were living at various moments in U.S. history, including shortly after the ratification of the Constitution in 1788 and at the start of the American Civil War in 1861.