Final answer:
Important minor parties in U.S. history often center around specific issues and charismatic leaders, impacting elections and major party platforms despite not winning broadly.
Step-by-step explanation:
Most of the more important minor parties in U.S. history have been of the type that champions a narrow set of causes and often emerges around charismatic leaders.
Their effects, while usually failing to secure broad electoral success, can be significant. The Progressive Party, for example, influenced the 1912 presidential election by pulling enough votes from the Republicans to assist in the Democratic win. However, these minor parties have often played a critical role in bringing issues to the attention of the major parties, who then sometimes adopt these issues into their own platforms.