Alright, let me tell you why the electoral college is one of the smartest things put into the United States constitution. If the vote was decided 100% on popular vote, 3 problems would occur:
1. Most Candidates would only focus on big cities (Chicago, LA, Atlanta, New York City) meaning that none of the smaller states would get a major say in the government. And for good reason, because there are a lot of people in those cities. However, those people tend to be all of the same party (democrats), which leads into my next problem.
2. Popular vote would mean that democrats win all the time. Which sounds great, but eventually the party will fracture into a niched system where you have communists, socialists, etc etc (basically different types of democrats). You'll end up with a lot of different parties, which means that your president will not have a majority of the votes, but only like 20%. However, you might say that popular vote is a better representation of all of america, which is false because:
3. With the electoral college, no one candidate can win with having appeal in one region. No region of the US (south, midwest, north-east, blah blah) has enough electoral votes to deliver someone the presidency. Look at Romney.
That's it. I'd love for someone to add to this or refute this, because it's fun arguing about things that I know about and that make sense to me.
1. You say this but it ignores existing problems with the electoral college system. With a popular vote system, EVERY vote counts, and they all count EQUALLY. One vote in rural Kentucky is worth the same as a vote in NYC. You say that candidates would only focus on big cities, but this doesn't make any sense. More than four out of every five people live in urban areas in the United States - 80.7%. And yet, according to you, all of these people are Democrats. Consider the fact that Donald Trump and Hillary Clinton got 62,000,000 and 65,000,000 votes respectively. If urban areas were all solidly Democratic, then Hillary would have easily won both the popular vote AND the electoral college, since those swing states should have swung for her. Unfortunately, it didn't happen that way. Your first point simply doesn't hold up to scrutiny, as the real-life makeup of urban areas are far more diverse than you give them credit for. You're falling for a media narrative of "liberal big cities"; while the largest, largest cities may be more liberal, they also only make up a very small portion of the population of urban areas.
2. The popular vote is not inherently favorable to Democrats. Let's go back all the way to Reagan, which is about when the existing set of politics started fragmenting and becoming the modern day demographical nightmare it is. Reagan got about 2-3 million more than Carter and Anderson combined. He then got 17 million more votes than Mondale. However, the next year, H W got only 7 million more votes than Dukakis.
It all switched to the Democrats when Bill Clinton joined in - however, Bill Clinton in his first election got about the same amount as Reagan did in his first election. The vote was split by Perot. In his next election, the same thing happened - Clinton got 47 million, and Dole and Perot combined for about 47 million.
Gore and Bush were split by about 600,000 votes and recounts were called off. Bush v Kerry was about a 3 million split. The big reason many people consider the popular vote to be solidly Democratic is because of Barack Obama, who got nearly 70,000,000 votes, the most ever by any Presidential candidate. Clinton, however, only got 65 million.
My point is this: Democrats do not have a solid lock on the popular vote. Republicans came out for Trump at about the same rate as Bush - and won both times, despite the Democrats having a solid swing in ups and downs. If the Democrats were truly in lock step with the popular vote, they would have not had the issues you're describing, which has required major splits in the past and major voter enthusiasm from Obama voters to muster up.
3. This is also the case for the popular vote - No region of the United States has anywhere near the popular vote to carry any one candidate. The Northeast has about 55 million, the Midwest about 66 million, the West about 74 million, and the South about 118 million. However, the South is also the least homogenous of these groups, with the heaviest demographical divides, making it impossible for that larger number to become utilized by a single candidate.
In fact, if you break it down even further, you'd find that the four largest sub-regions: the South Atlantic, Pacific, East North Central, Mid-Atlantic are all within 20,000,000 population of each other, are in the South, West, Midwest, and Northeast. The population of the United States is pretty well spread out and mixed, making your fears of solid voting blocs to be unfounded and based on, again, a narrative of "south conservative" and "north liberal".
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So not only is the popular vote not inherently favorable to big cities, but it is also not favorable to Democrats, and would isolate regions from wielding large power over one another.