Don't you mean this country is dominated by a 2 party system? I don't think it's written anywhere that it has to be a 2 party system.This country has a 2 party political system. A third party candidate will never be eleced. Not ever. When was the last time a 3rd party got more the 5% of the vote except for Perot, and he didn't really want it. Libertarian party never runs a candidate worth voting for, and no one will vote for a candidate that thinks you should do whatever you want to do. We have to have laws.
Are you one of those I don't want to "waste" my vote crowd. You should be voting for who ever you want to be your candidate/choice. Over strategizing the vote is what has lead this country down he river for decadess. Vote for your actual choice in candidates and propositions. Comprimise or settling for the lesser of two evils is what politician tell their sheeple to do. Who says the sheeple will follow only one of two leaders.