Several people have asked why Clinton lost the election despite having more votes overall (winning the popular vote). If the electoral college was representative of the populations votes, surely it should be more in favor of Clinton?
Well, one factor is that the electoral college system is currently biased towards red states. Staunchly Republican states have on average approximately 450k people per electoral college vote. Whereas staunch Democratic states have an average ~550k. If you take out rinky-dink little states like New Hampshire and Rhode Island, the value is closer to 600k per electoral college vote.
The more conservative states are skewed even more: Wyoming las less than 200k people per vote. N Dakota has 230k, S Dakota has 280k, Montana 330k, and Nebraska 360k per vote. Rural midwest areas have populations that are relatively declining in size. Whereas, urban areas have expanding populations but the electoral college votes has not kept pace with the population size. For example, New Jersey, New York and California are around 700k people per vote. Virginia, which is now a Democratic leaning State, is expanding rapidly in the north and has 630k people per vote.
If California had the same electoral vote per population rate as a fairly populace and growing red state (e.g. S Carolina with 530k per vote) it would cast 72 electoral votes for Clinton instead of 55. New York would have had 37 votes instead of 29 etc. If California had ratio of electoral college votes per head of population as Wyoming does, Californian would have 192 votes (and New York would have 99).
In short the Republican supporting mid-west States haves far more impact in the electoral system than the democratic leaning coastal states. It's an undemocratic system at present. It could, however be fixed if electoral college votes were proportional to population. However, currently Republicans get an advantage in the electoral college system, so a Republican controlled Congress has been reluctant to change the system so that it is fairer.
However, usually the popular vote (the proportion of votes cast for a candidate) has also matched the electoral college vote. There have only been five times that the winner of the electoral college vote lost the popular vote: John Quincy Adams in 1824; Rutherford Hayes 1876; Benjamin Harrison 1888; George W. Bush 2000; and now this year. The recent mismatches between popular and electoral college voting is due to this disparity between votes and population.
Sp why not do away with the electoral college system? Well that would require clear Democratic majority, as Republicans like the status quo, which supports them. Also doing away with the electoral college system may not be a good thing. It was originally developed to ensure that a candidate that was popular in one just one small region of the US couldn't be elected. There had to be widespread support. Arguably what has happened in the US is exactly what the 'founding fathers' of America feared.
Alexander Hamilton said that the electoral college system was set up because the electors would ensure “the office of president will never fall to the lot of any man who is not in an eminent degree endowed with the requisite qualifications”.
Well that worked out ...