A democratic system does not simply mean voting by the people. The devil lies in how it is administered and executed. If being corruptly manipulated, the system may elect an evil person against the will of the people. Since no system is perfect and foolproof, a democracy must be carefully maintained to ensure fairness and the public good. It must also be simple enough so that all citizens are encouraged to come out and vote.
In a large continental country like the United States, the nationwide popular vote does not matter although the vote count is published. What matters is the electoral vote (also known as electoral college) as defined by the US Constitution. Each state takes full responsibility for its own elections from city to national level. The state divides its own territory into a number of congressional (or electoral) districts according to the population count taken by the US Census every 10 years. For instance, California, the most populous state, has 53 congressional districts (versus Texas 36 and New York 27). That means California sends 53 Representatives to the US House of Representatives, Texas 36 and New York 27. Each Representative is elected by the people living in his/her own congressional district. So each state has a diverse representation to the US House with respect to their different economic and other interests. Consequently, US national policy is theoretically driven by competing interests from all the 435 Representatives of the states of the federal Union, which are in turn driven by the voters living in all the local congressional districts. However, in practice it does not work that way. History has shown that some Representatives have become very powerful and carry bigger sways in federal decision making due to their personality or manipulating skills. There also exist other important factors as described below.
Besides the House of Representatives, there also exists the US Senate where all federal legislation must be passed before becoming effective. As defined by the US Constitution, each state elects two Senators to the US Senate regardless of its size. Thus the state of Wyoming with the smallest population of 0.56 million elects 2 US Senators, so does California with a population of 39.54 million. Consequently in the US Senate, California, despite being the most populous state, carries the least weight relative to all the other states. History has also shown that some Senators from smaller states have exerted a disproportional amount of influence on national policies. You may think that this is unfair but that reflects the nature of the American democracy where each state voluntarily joined the Union at different times in history by negotiation, not by coercion. The Senate system is one way of ensuring that the voices of the smaller states are not being drowned out by the bigger ones.
What about election of the President? The US Constitution stipulates that each state takes full responsibility of the election. The people living in each congressional district elect one presidential candidate in early November of an election year. The US Representative of that district is obliged (not bound by law though) to cast one electoral vote for that elected candidate in mid December of that year for the purpose of confirming the result of the election. In effect, there is no direct popular vote in the United States. The people vote for the elector who is the US Representatives of each district who will in turn cast one electoral vote for the people. The total electoral votes amount to 538 and it requires 270 votes to win the presidency. Each state is given a number of electoral votes equal to the number of Representatives plus 2 Senators. Thus California has 55 electoral votes, Texas 38 and New York 29. Think about this scenario: If an elector casts one vote for the other presidential candidate by ignoring the will of his constituents, it may flip the result if the election is a very close one.
Another major concern with the electoral college is the winner-take-all state rule for presidential election that is not stipulated in the US Constitution. Take California for instance, if 28 electors vote for a presidential candidate (the smallest majority), that person will get all the 55 votes allocated to California. Despite its unfairness on the surface, this winner-take-all rule apply to all 50 states except Maine and Nebraska.
A third major concern is voter suppression. The black votes have traditionally been suppressed in the Southern States although the Voting Rights Acts enacted in 1964 have reduced the problem. Fewer people coming out to vote usually benefits the Republican Party. That is why this party complains loudest about voter frauds which are more invented than real. The excuse of voter frauds makes stringent voting requirements necessary so that lower-income blacks and minorities tend to stay at home due to all the voting hassles targeted at them.
We all know that money corrupts every man-made system. American democracy is no exception because people are subject to material seduction. The evil of money politics has been around for a long time. Efforts to reform the American election system date back to almost the beginning of the nation but to no avail. Two factors have made it very hard to achieve reform. First, it takes millions of dollars to run a political campaign to drive an issue or to elect a politician. It is much easier to ask a few rich people or corporations for donation money than to raise millions of dollars from thousands of ordinary citizens. Besides, rich people or corporations will gladly come to the politicians to offer campaign money (legally known as political lobbying) because they want to promote their own self-interests rather than the public good. Bribing the politicians with money disguised as campaign contributions is considered legally acceptable in America.
So we see a democracy is messy and ugly and must be carefully and fairly maintained. Nevertheless, it is still better than an absolute monarchy, a dictatorship or an authoritarian regime where money and power are allowed to corrupt the system openly without any restraint.