Some European countries have an automatic or instant runoff, if no candidate receives a majority of votes. The ballot allows for the voter to choose a first and second choice. This allows for voters to register their true choice as first, often a 3rd party candidate, and then a 2nd choice, usually one of the expected top two vote getters. The Green Party in the US promotes this way of voting, allowing Green voters to register their first preference, but having their lesser of 2 evils as the 2nd choice. The computer automatically recalculates all votes for the top two candidates by reassigning these 2nd choice preferences, making a new campaign run off between the top two candidates unnecessary. For example, if Hillary Clinton and Donald Trump were in a close race, Green Party voters would be tempted to vote for Hillary Clinton over Dr. Jill Stein their real preference. With an automatic or instant runoff, they would not fear voting their first choice, as if Trump failed to get a majority, an instant runoff would allow the Green votes to be reassigned to Hillary Clinton, and perhaps give her the majority needed to win electors in a given state. The instant runoff saves money both for the candidates and for the government or taxpayers financing the state election process, and allows voters to be free to indicate their real first preference for a candidate. The two majority US parties tend to oppose the idea, as it gives 3rd parties more power. Also, now Democrats and Republicans can blame the 3rd party candidates, as Gore blamed Ralph Nader for his Florida loss and some Clinton supporters blame Dr. Stein for the Trump win. Another reason we may not yet have this system is the slight math complexity involved. America has not led the world in mathematics education.