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 augmented legislative representation in states with enslaved people by incorporating three-fifths of their slave populations into the free population count. This method, referred to as the Three-Fifths Clause or "federal ratio," was employed for determining congressional districts and Electoral College delegates.