It may be the only one of the major countries holding elections this year where a presidential candidate could win a majority of the votes and lose the election. This is because of America's Electoral College system, a bizarre remnant of the formation of the union.
One of the basic concepts of the United States of America is representative government -- that if it is the will of the people to change something it can be changed. But not the Electoral College. "Representative" in principle should mean "flexible." But what it comes down to is that American democracy does not mean one person, one vote, at least not when it comes to the presidency.
The other hammerlock that tradition has on democracy in the United States is the two-party system. There is an argument that President Barack Obama would have benefited from a challenge within the Democratic Party from the right or the left, but no such luck.