The Electoral College is frequently a mystery even to Americans who have followed many Presidential elections. This is a historical explanation of what the Electoral College is, why it came about, how it works, and some possible problems with it.

In the early years after the Revolution, the United States of America was governed by the Articles of Confederation.[i] It was an unhappy experiment. The Confederation Congress needed to get 9 of the 13 states to agree to pass any measure, and had no power to enforce its laws on the states. States failed to pay their contributions, even ones to which they had agreed, leaving the Confederation Congress broke much of the time. The situation in the states was not much better. In 1786, Massachusetts’ government seemed on the verge of toppling to a rebellion of farmers.[ii]

So when the delegates from 12 of the states gathered for the Constitutional Convention in Philadelphia in 1787, they decided to build a stronger central government. They wrestled with many controversies, and typically adopted compromises to obtain the broadest possible support. They made the new Federal Government more powerful, but split it into three branches, and made each a check on the other two.[iii] In the conflict over whether the Federal Government should represent the states or the people, they compromised and created a legislative branch, Congress, divided into two chambers: the House of Representatives, to represent the people, and another, the Senate, to represent the states.[iv] And in the conflict between being responsive to the popular will and preventing the government from being subject to momentary mob enthusiasms, they gave members of the House of Representatives only a two-year term, while giving Senators a six-year term, and having the judiciary appointed by the President subject to review by the Congress.[v]

Ah, but how was the President, the head of the executive branch, to be selected? The Constitutional Convention enacted a complex system along the lines of their previous compromises. The President would be elected, thus representing the popular will, but not directly. Instead, he would be elected by a special group of people chosen for that purpose called electors, which group we now call the Electoral College.[vi] These would be chosen by the states, giving them a role. Each state would get two electors just for being a state, just like how they get two Senators in Congress. But they would also get the same number of electors as they have Representatives in Congress, hence in proportion to their population, which gives the popular will a role once again. The electors would be the ones who would actually cast votes for the President, and also vote separately for the Vice President. Whichever candidate got a majority of the Electoral College votes would become the President and Vice President.[vii]

Over time, certain customs developed in the election of the President. Under the Constitution, legislatures determined how the electors were chosen from their state. In the early days, many legislatures did choose the electors, but over time the legislatures turned the choosing of the electors over to a popular vote. And the “winner take all” principle became the norm: whichever candidate won a plurality in each state would get all the electoral votes from that state.[viii]

So how does this actually work today? Each state gets as many electors as it gets Senators and Representatives in Congress. Each state gets two Senators, so each state gets two electoral votes for that. The 435 Representatives in the House are apportioned roughly by population, so each state gets electors roughly proportionate to the population.[ix] For example, California, the largest state by population, gets 53 electors because it has 53 Representatives, plus the two electors it gets for having two Senators. Wyoming, the smallest state by population, gets only one electoral vote for its one Representative, but two more for its Senators, so three in total. And there is one anomaly: the District of Columbia is represented in the Electoral College as if it were a state, so it gets three electors.[x] Hence there are 538 electors (435 + (50 x 2) + 3). For a candidate to win the Presidential election, that candidate must win over half the Electoral College votes, which means 270 are needed to win.

When you go to vote on November 8, the ballot you mark probably lists the names of the candidates, but you are actually voting for the slate of electors in your state that have been nominated by each candidate’s party to pledge their votes for that candidate. The candidate who wins a plurality in each state wins all that state’s electoral votes, which is to say that candidate’s electoral slate is deemed the winner.[xi]

Once the appropriate state official certifies the vote, and hence the election of the winning electors, those electors gather at the state capital to cast their votes, which are then certified by state officials and carried to Washington, D.C. There in January, the new Congress will count the Electoral College votes and declare the winners of the Presidential and Vice Presidential elections.

Simple. Even though the President isn’t officially elected until the Electoral College votes are counted by Congress in January, we’ll almost certainly know the day after people vote in November who won.

But what if something goes wrong? There are three perfectly legal problems that could cause the Electoral College to fail.

The first and biggest problem with the Electoral College is that a candidate can win the popular vote and still lose in the Electoral College. There are two reasons why this can happen. First, the Electoral College rewards winning in small states disproportionately to winning in large states, because small states have their weight in the Electoral College increased above their population thanks to the two electors they get just for being states (corresponding to the number of Senators they have). Second, the winner-take-all system of awarding all the electoral votes of a state to the winning candidate means a candidate can barely eke out a popular vote majority in just enough states to win the Electoral College, while being thoroughly trounced in the other states.

It’s happened three times: in 1876, 1888, and 2000, the candidate who won a plurality of the popular vote lost in the Electoral College to an opponent who had gathered a majority in the Electoral College.[xii]

There’s not much that can be done about this. It’s part of the design of the Electoral College. But in these more democratic times, when we feel the will of the people should be the final word, results like these undermine the legitimacy of the Presidential election process and the Presidency.

The second problem is that, while the electors are typically chosen from loyal party members who cast their ballots as directed, sometimes electors don’t vote the way they’ve been instructed by the voters and their parties. It’s only happened occasionally, as recently as 2004, but has never influenced an election’s outcome yet.[xiii] Still, such votes are legal and irreversible. Oh, some states have passed laws binding electors to vote in accordance with the popular vote, but the Constitution recognizes no such constraints on an elector’s vote. The authors of the Constitution looked at the electors as being local wise men who would vote for a reputable statesman, not party hacks who would blindly follow a popular vote.[xiv] So it’s questionable whether those state laws could actually bind the electors, to say nothing of overturning the votes they actually cast.[xv] Neither the states nor Congress have disputed the votes of rogue electors. Conceivably, if enough electors changed their mind, they could elect someone nobody voted for.

The third problem is if no candidate wins a majority of the Electoral College, which given the current even number of electors includes the possibility of a tie. It happened once under the current system, in 1824.[xvi] In that case, the election for President is thrown into the House of Representatives. But, contrary to what you might expect, the Representatives don’t vote directly for the President, no. Instead, they have to band together and vote by states, each state getting only one vote. So, if this situation arose, California would have to get its 53 Representatives to huddle and decide which candidate they would cast their one vote for. Imagine the misfortune of a state with an evenly split delegation: it wouldn’t be able to cast a vote at all! While the smallest states, with only one representative, would have an easy time of it.

It was a mess when it happened in 1824. Two of the also-rans, John Quincy Adams (who came in second) and Henry Clay (who came in third in the popular vote, fourth in the Electoral College vote) banded their supporters together to give Adams a majority in the House, and hence the Presidency. Andrew Jackson, who had won a plurality of both the popular vote (41%) and the Electoral College vote (99 out of 261) felt the election had been stolen from him. His successful campaign four years later against Adams was heavily colored by charges that Adams and Clay had made a corrupt deal in 1824.

It wouldn’t be much better today. In the current Congress, 33 state delegations have a majority of Republicans, 14 of Democrats, and 3 are evenly split. The Democrats may pick up a delegation or two in this election year, but the Congress that meets in January, 2017, is still likely to have a majority of state delegations with Republican majorities. Say that the Democratic nominee, Hillary Clinton, wins a plurality of votes and Electoral College votes, but not a majority, because the rest are split between Donald Trump, the Republican candidate, and Gary Johnson, the Libertarian candidate. How many Republican delegations would be willing to vote against their own party to put Ms. Clinton in the White House? Or what if Mr. Trump’s behavior continues to erode his support? Might the Republicans decide they should discard all the losing nominees, and elect a stalwart Republican they like?[xvii]

Fortunately, the possibility that neither Mr. Trump nor Ms. Clinton will win a majority in the Electoral College is still remote, so this third difficulty is still unlikely . . . so far.

[i] The Articles were accepted by Congress in 1777, but were not ratified by all the states until 1781.

[ii] This was Shays’s Rebellion. The rebels felt that the economy and laws had been manipulated to benefit speculators. The state government viewed the uprising as treason, pure and simple.

[iii] The three branches are the legislative (Congress), responsible for passing laws, the judiciary (the Supreme Court and other Federal courts), responsible for judging cases under law and the constitutionality of laws, and the executive (the President and the executive branch agencies), responsible for the administration, execution, and enforcement of the laws.

[iv] In the House of Representatives, each state has representation in proportion to its population, while in the Senate each state gets two votes, no matter how many people live in that state. This also resolved the controversy between the large states, which wanted their votes to represent their size, and the small states, which wanted each state to have equal representation. One should also note that who counts as a person and who votes were not simple matters in 1787, let alone the same thing. Native Americans not actually subject to the Federal Government’s authority (“Indians not taxed” in the phrase of the era) were neither counted nor could vote. Slaves were counted as 3/5ths of a person and could not vote. Women and children were counted but could not vote.

[v] As the House represented the people directly it was appropriate that it had the shorter term, the better to respond to popular views. The Senate, on the other hand, was not just apportioned equally to each state, but its members were originally elected, not by the voters, but by the state legislatures. Hence their role as a “cooling vessel” for public passions in legislation. It was only in 1913 that the ratification of the 17^th Amendment to the Constitution gave the power of electing Senators to the voters directly, instead of the state legislatures.

[vi] It was assumed that any Presidential candidate would be a man. The people in the Electoral College are called “electors” because their purpose is to elect the President.

[vii] The original system used in 1788-1800 was different in that the votes for President and Vice President were not distinguished. This created controversial problems in the elections of 1796 and 1800. The current system was put into place with the 12^th Amendment to the Constitution, ratified in 1804. There have been other minor changes since then.

[viii] A candidate who gets more votes than any other candidate is said to have won by a plurality. If the candidate wins over 50% of the vote, the candidate is said to have won by a majority. Every majority is a plurality, but not every plurality is a majority. For example, in a three-way race, a candidate who wins 40% of the vote while the other two candidates won only 30% of the vote apiece has won by a plurality, because the first candidate’s 40% share is bigger than either of that candidate’s opponents.

[ix] The correspondence between population and size of a state’s delegation in the House of Representatives is not exact for three reasons. First, the number of Representatives has been fixed by law at 435 since 1929, and fractional representation isn’t allowed; there are going to be rounding errors. Second, each state is guaranteed one Representative no matter how small its population, which means some small states are disproportionately overrepresented. Third, there are several possible algorithms to apportion the remaining seats, but none of them gives a perfect result.

[x] This has been true only since the 23^rd Amendment to the Constitution was passed in 1961, with the additional provision that the District can never have more electoral votes than the least populous state. Under current circumstances, both rules give the District three electors.

[xi] Maine and Nebraska are currently exceptions. They award Electoral College votes both by statewide election and by the vote in each Congressional district. So, for example, if candidate A wins the statewide vote in Maine and in Maine’s 1^st Congressional district, but candidate B wins in Maine’s 2^nd Congressional district, candidate B would get 1 electoral vote from Maine, while candidate A would get 3 (1 for the Congressional district, 2 for winning the state as a whole).

[xii] Note this description does not fit the 1824 election, in which no candidate took a majority of the Electoral College. 1824 is a special case discussed later in the text.

[xiii] The most recent cases have been protest votes in which the elector didn’t vote or voted for another member of their party. The last elector to vote for another party’s candidate was in 1972. Technically, the rogue electors of 1836 did change the election, since their actions forced the election into the Senate (see footnote xvii), but the candidate who should have won in the Electoral College did win in the Senate.

[xiv] The development of nationwide political parties was not anticipated by the delegates at the Constitutional Convention. And given the slow communications and the large size of the nation back then, the rise of a number of regional parties probably appeared more likely.

[xv] After an elector cast a protest vote in 2004, Minnesota changed its rules so that electoral votes could be reviewed before being certified. To date, this mechanism has not been tested by a rogue elector trying to cast a vote for the wrong candidate, so its legality at the Federal level is uncertain. The Supreme Court has held that states can require electors to pledge to support a candidate, but has not ruled in favor of any mechanism to enforce that pledge.

[xvi] There was a tie in 1800, but that was under the older system. See footnote vii.

[xvii] What about the Vice Presidency, you ask? If no candidate wins a majority, that election is thrown into the Senate, where each Senator casts an individual vote. This has happened once, though not in 1824, surprisingly. It was in 1836, when the Democratic candidate, Richard Mentor Johnson, fell one vote shy in the Electoral College, but was elected by the Senate. Johnson was a controversial figure because he had lived with a mixed-race slave as if she were his wife, and that caused several electors to drop him from their ballots, although they still voted for his running mate, who became President Martin Van Buren. The most curious possibility that might arise in the 2016 election would be if no candidate won a majority in both the Presidential and Vice Presidential races, while the Democrats managed to recapture the Senate. If both chambers stuck to party loyalty, the result could be a Republican President and a Democratic Vice President. The last time the President and the Vice President came from different parties was in the election of 1796! (One could argue that John Tyler and Andrew Johnson were subsequent examples, but they ran on the same party ticket as the Presidents with whom they were elected.)