Prior to the passage of the 12th Amendment, each member of the Electoral College voted for two candidates, with no distinction as to whether the vote was for president or vicepresident. After the votes were counted, the candidate with the most votes would become president, while the one with the second-most votes would be vice president.
However, the election of 1800 saw Jefferson and Burr each winning 73 electoral votes. Moreover, Adams won 65 votes, while Pinckney won 64. After this outcome, it was unclear how the offices should be awarded. This confusion led to the passage of the 12th Amendment. As a result of the amendment, the electoral college now votes for president and vice president separately.