Here’s what it was:

• During the Constitutional Convention, delegates debated how enslaved people should be counted for purposes of representation in Congress and taxation.
• Southern states, which had large enslaved populations, wanted enslaved people fully counted to increase their representation in the House of Representatives.
• Northern states, where slavery was less prevalent, argued that enslaved people shouldn’t be counted at all, since they were denied rights of citizenship.

The compromise they reached was:

• Each enslaved person would be counted as three-fifths of a person for both representation and taxation.

This meant:

• Southern states gained more seats in the House of Representatives than they would have if enslaved people were excluded entirely.
• But they gained fewer seats than if enslaved people had been counted fully.

The Three-Fifths Compromise was later rendered obsolete after the Civil War. The 13th Amendment (1865) abolished slavery, and the 14th Amendment (1868) mandated that representation be based on counting all persons equally, regardless of race or legal status.

👉 It’s often cited today as an example of how the Constitution both accommodated and entrenched slavery in the early United States.