Final answer:
By 1840, slavery had been outlawed in most of the Northern states. Slavery had existed in the South since 1619, but Northern states began gradually abolishing it after the American Revolution.
Step-by-step explanation:
By 1840, slavery had been outlawed in most of the Northern states (c). Slavery had existed in the South since at least 1619, but Northern states began gradually abolishing the practice soon after the American Revolution. In the more rural and agrarian South, slavery became a way of life. By 1790, there were over 650,000 slaves in the South, and by 1810, that number had increased to over 1.1 million individuals.