Article 1, Section 2, of the US Constitution supplemented legislative representation in states whose residents owned slaves. Known as the Three-Fifths Clause, or the "federal ratio", three-fifths of the slave population was numerically added to the free population. That sum was used for each state to calculate congressional districts and the number of delegates to the Electoral College.
Article 1, Section 2 of the US Constitution increased legislative representation in states with enslaved individuals by counting three-fifths of their slave populations as part of the free population. This practice, known as the Three-Fifths Clause or "federal ratio," was used to calculate congressional districts and Electoral College delegates.