The Constitution (ratified in 1789): Article II, Section 1, carefully defines the voting procedure to be followed by electors. Originally, the electors were to vote for the two most qualified persons without noting which of the persons was selected as president or vice president. The candidate receiving the greatest number of electoral votes, provided the votes of a majority of the electors were received, would be president, and the candidate winning the second largest number of votes would be vice president.

1796: The first flaw in the system occurred when John Adams and Thomas Jefferson were elected president and vice president, respectively. Political parties were not established back then, but the candidates had decidedly opposing viewpoints.

1800: A majority of electors voted for both Jefferson, head of the Democratic- Republican Party, and Aaron Burr (1756-1836; see box in Thomas Jefferson entry in...