The 12th Amendment, which combines a party’s presidential and vice presidential candidates onto one ticket, turned 209 this weekend (ratified June 15, 1804). 

Until this amendment was passed, the president was the winner of the election and the vice president was the runner up, regardless of party affiliation or beliefs; and until the Adams-Jefferson administration, there had never been a president and vice president from different tickets.

The election following this tense leadership resulted in a tie between Jefferson and Burr, in which the House of Representitives had to decide. 

 

The full text of the amendment can be read at Constitution Daily