For most of Iowa's history, activists have gathered in the winter to deal with politics, but no one outside the state paid attention until 1972, when Democrats established their caucuses in January. That made the party's presidential preference vote the first in the nation, and candidate George McGovern, encouraged by his campaign manager Gary Hart, took advantage by campaigning in Iowa and finishing a stronger-than-expected second place. McGovern's showing helped propel him to the Democratic nomination, and four years later it did the same for a little-known governor from Georgia, Jimmy Carter.

The Republicans joined Democrats with the early caucus date in 1976. Since then Iowa has drawn more candidate visits and media attention with each campaign.