In the u. s. political system, a vote for a minor party candidate is considered a wasted vote. what election reform would decrease the likelihood of a vote being wasted on an unelectable candidate?

Reforming the first past the post winner takes all system as explained by the divulger's law.

The law explains that first past the post political system like the one in USA tend to favor two party system making it very hard for minor candidates to win in an election. they thus call for proportionate  plurality that favors multipart ism.