Under the constitution, the election for president is thrown into the US House of Representatives, while the Senate picks the next vice-president (the Senate's presiding officer).
The 'unit rule'
But while the Senate simply requires a majority of its 100 members to select the vice- president, the House must vote by states, with each state delegation having a single vote, and a majority of the states (at least 26 of 50) required to agree on the winner.
Thomas Jefferson: The unit rule was fairer in 1800 than it is today
This is called "the unit rule". The founding fathers centred the idea on the fact that the nation was a confederation of states rather than a pure democracy of individual voters. Just as the electoral college is state-based, the House selection of the president in the case of deadlock revolves around the states.
The unit rule has been employed twice in US history, in the long-ago elections of 1800, when Thomas Jefferson emerged as president, and 1824, when John Quincy Adams was elected.
Both elections were controversial, but not mainly because of the unit rule. Two centuries ago, the unit rule was less undemocratic since population disparities among the handful of states were smaller, and Americans were much more accepting of elite control and a lack of popular sovereignty.
Think about what House selection of a president would mean today. Gargantuan California would have the same single House vote in choosing the new president as sparsely populated Wyoming, even though California has about 70 times its population. The votes of the mega-states of Florida, New York, and Texas could be cancelled out by the tiny populations of Montana, Rhode Island, and South Dakota.
Furthermore, large state delegations could internally deadlock via tie votes. Some large states might be deprived even of their single vote for the presidency. Tens of millions of people could be disenfranchised in this fashion.
Meanwhile, all the small states with single House members will certainly be counted. The smaller the House delegation, the more likely the state's House members will be able to reach agreement or at least finish their tally. All pigs would be equal, but in this odd Orwellian case, the tiny pigs would be more equal than the huge ones.