Three-Fifths Compromise: The first instance of black slaves in the United States of America being counted as three-fifths of persons (for the purpose of taxation), in a resolution of the Congress of the Confederation. This was later adopted in the 1787 Constitution.

The Three-fifths Compromise, also known as the Constitutional Compromise of 1787, was an agreement reached during the 1787 United States Constitutional Convention over the inclusion of slaves in counting a state's total population. This count would determine the number of seats in the House of Representatives, the number of electoral votes each state would be allocated, and how much money the states would pay in taxes. Slave states wanted their entire population to be counted to determine the number of Representatives those states could elect and send to Congress. Free states wanted to exclude the counting of slave populations in slave states, since those slaves had no voting rights. A compromise was struck to resolve this impasse. The compromise counted three-fifths of each state's slave population toward that state's total population for the purpose of apportioning the House of Representatives, effectively giving the Southern United States more power in the House relative to the Northern United States. It also gave slaveholders similarly enlarged powers in Southern legislatures; this was an issue in the secession of West Virginia from Virginia in 1863. Free black people and indentured servants were not subject to the compromise, and each was counted as one full person for representation.