As you may have noticed, I talk a lot about third parties on my blog (primarily on the libertarian/minarchist side of the house). That's because there are loads of other political blogs out there, and they generally tend to focus on the Republicans and the Democrats. I like to think I'm doing my part to get the word out about the various other options that are available.
Getting back to the main point of this post: the reason a third party will never win an election in the U.S. I'm often quick to blame the voters, because nearly everyone I've ever discussed third parties with considers a vote for a third party a "wasted vote." Essentially, they won't vote for a third party because they don't believe that party will win. This of course turns out to be a self-fulfilling prophecy and creates circular reasoning that further fuels the cycle of avoidance of third parties.
The lack of voter support is certainly a rational reason, but what began this vicious cycle in the first place? In order to discover that, we need to travel back in time, to the early years of our country.
The Founding Fathers
The first two parties to take over politics in the United States were the Federalist Party and the Democratic-Republican Party.
Eventually, the Democratic-Republican Party split into the Jacksonian Democrats (which later evolved into the modern Democratic Party) and the Whig Party.
The Republican Party rose in the second half of the 1800s, and adopted many of the economic polices of the Whig Party.
A Republican or Democrat has won every presidential election since 1852, and either party has controlled Congress at one point or another since at least 1856.
The Vicious Circle
As you can see from this diagram, voters are only a small portion of the problem. The United States' election system itself is also to blame.
Obviously, the Republicans and Democrats who benefit from the system have no interest in changing it to really give third parties a chance.
If you've never looked at any of the platforms of the various third parties of the United States, then I highly suggest it. You may just find that they're more in line with your own than either of the two major parties. Here are some links to get you started (and be aware there are many more third parties out there):
The Libertarian Party Platform
The Green Party Platform
The Constitution Party Platform
The Socialist Party Platform
Even if you decide that a third party isn't for you, then you can still help improve U.S. politics by encouraging your friends to vote if they don't. I also encourage you to vote as well, if you don't already. I think it's kind of embarrassing that the highest voter turnout we're generally able to muster is 40%. You'd think more people would be concerned with the fate of our country.