For the second time in sixteen years, a presidential candidate who won the popular vote will not win the Electoral College--and, consequently, the presidency--bringing up again an intense debate over which method should be used to determine the President of the United States.
Each state is given a number of "electors" who cast "electoral votes" for one candidate or the other based on which candidate won the popular vote within their designated state. In other words, in every state other than Maine and Nebraska, the winner of the popular vote in that state receives all of that state's electoral votes. Though there is technically nothing stopping an elector from casting her vote against her state's popular vote, it is exceptionally rare for an elector to do so and has never altered the result of an election. The candidate with the most electoral votes wins the election.
The amount of electoral votes each state gets corresponds with the number of its congressional representatives (which, in turn, is based on the state's population). Arizona, for example, gets eleven electoral votes because it has nine representatives in the House of Representatives and two representatives in the Senate. Under the current "winner take all" approach, Donald Trump will receive all eleven of Arizona's electoral votes since he won the popular vote in Arizona, despite the fact over 45% of Arizona's voters voted for Hillary Clinton. Likewise, Clinton will receive all of California's 55 electoral votes, despite Trump receiving almost 33% of the vote there.
Why the Electoral College under a winner take all method? When the United States was formed, methods of transportation and communication were clearly not as advanced as they were today; an attempt to collect, tally and report every single vote would have proved difficult. The government was also worried that limited access to information would lead voters to make uneducated votes and did not trust a system where every single citizen had an equal say in the matter. As a compromise, they decided it would be better to have intelligent electors who could meet in one place and cast their votes as a representation of the general consensus of their designated areas.
Southerners were also concerned about protecting their institution of slavery and other conflicting interests with the north. Because the black population was not allowed to vote, the northern states' eligible voter population outnumbered the south considerably. A popular vote would have given the north the edge over any conflicting interest, including slavery. An Electoral College that took into account 3/5 of the black population ensured interests of the south were protected.
Why consider the popular vote now? For one thing, advances in transportation and communication make a popular vote easy to collect, tally and report; we can literally watch the updated numbers by the second on our home televisions and computers. Though the Electoral College was also designed to protect against uneducated voting, the modern voters' ability to access a plethora of information, including false information and propaganda, has arguably rendered the Electoral College about as useless as a popular vote in protecting against this. Under the winner takes all approach, the electoral system dissuades democrats from voting in red states and republicans from voting in blue. It forces candidates to focus too much time on states that are undecided rather than the nation as a whole. In a two party system, it renders the legitimate inclusion of a third party option unrealistic if not impossible.
Why keep the Electoral College now? Smaller rural communities are concerned that a popular vote would be dominated by the heavily populated urban areas. Though there is thankfully no longer a conflicting interest over an institution like slavery, many urban and rural communities do have different interests, cultures, beliefs, agendas and priorities they would like protected. The Electoral College gives smaller areas a stronger voice in a national conversation.
A trending compromise is to get rid of the "winner take all approach" and develop a system where electors vote based on the popular vote winner of their district rather than the entire state. Nebraska and Maine already do this. Getting the other 48 states on board could resolve a lot of issues with the current system.