Their strong sense of common interest enabled the slaveowning planters to become the most politically powerful social group in the United States. They dominated southern state governments. The Constitution’s three-fifths rule (counting five of their slaves as three free persons) enhanced their representation in Congress and the electoral college. In 1815, they had held the presidency for twenty-two of the past twenty-six years, and they would control it for all but eight of the next thirty-four.
