In 1776, when the colonists declared their independence and formed the United States, 500,000 enslaved people lived in the new nation, comprising one-fifth of the total population of the United States. 10,000 of the new nation's inhabitants were enslaved people, which was 4 percent of the total population. the enslaved population was at its peak in American history and would decline rapidly in the decades ahead. all enslaved people became free.