In the Presidential Election of 1800 Thomas Jefferson received 73 electoral votes compared to John Adam’s 65. Because of the 3/5th’s Compromise, The compromise gave the slave states 14 extra electoral votes and Jefferson received 12 of the 14. Without the 3/5th’s compromise Adams would have won the election by a margin of 65 to 61.
10 of the first 12 Presidents owned slaves and 18 of the first 31 Supreme Court Justices owned slaves.