Two political parties dominate the U.S. electoral system. Ever since the party system emerged in the 1800s, presidential elections have gone to either Democrats or Republicans. In the final installment of our series on political parties, we take a look at the role third parties play. The main alternatives to the top two are the Green Party, the Libertarian Party and the Constitution Party. None are on the ballot in all 50 states. Can Native voters find what they are looking for in a third party? Can a third party candidate make it to the White House?