For much of U.S. history, ordinary Americans had little say in how parties nominated their presidential hopefuls. Nominations were largely decided by party leaders across the states.
But things changed in 1968 when riots ensued at the Democratic National Convention when delegates fought over who should be the Democratic nominee in that year's presidential election.
While some states held primaries in 1968, it was not uncommon for a popular statewide candidate to run as a "favorite son" in order to win that state's delegates and have a major say at the convention.
Following the debacle at the 1968 Democratic National Convention, parties tended to shift to allowing voters to have a larger say in nominating their party's standard-bearer.
How good of a bellwether are the Iowa caucuses?
Past GOP Iowa caucus winners include Ted Cruz, Rick Santorum and Mike Huckabee. None of them would win the party's nomination.
Iowa caucuses are born
With much more emphasis placed on primaries and caucuses, Iowa decided to have its Democratic caucuses on Jan. 25, becoming the first state to have a nominating contest in 1972. About 20,000 Iowans showed up, but a plurality – 36% – were uncommitted to any candidate.
Despite being a long-shot candidate, George McGovern came in second place, behind Edward Muskie. This gave his campaign an early boost and proved he could be a formidable candidate against 1968 Democratic nominee Hubert Humphrey. McGovern ended up earning the nomination that year.
But it was the 1976 Iowa caucuses that cemented its status as an important nominating battle. Georgia Gov. Jimmy Carter came in first place with nearly twice as many votes as second place Sen. Birch Bayh.
What Carter's win showed was that a Washington outsider could be popular among voters and not those who previously had a larger say in deciding the nominee. Carter's eventual nomination likely would not have happened without changes to the Democratic Party's nomination process.
Meanwhile, Republicans opted to have their first Iowa caucuses in 1976. Although the 1976 election featured sitting President Gerald Ford, former California Gov. Ronald Reagan's entry made for a tight nominating contest.
In 1976, Iowa turned out to be a major bellwether for that year's GOP nomination process. Ford won the Iowa caucuses narrowly. It wasn't until that year's Republican National Convention that Regan decided to exit the race.
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How 2020 changed Iowa's role
For nearly five decades, the Iowa caucuses were seen as important for both Republican and Democratic candidates. Although the two parties have used different formulas for divvying delegates out of Iowa, the fact that Iowa has been at the start of the election calendar has meant the Midwestern state has had outsized influence in picking nominees.
But the 2020 election changed that for Democrats.
Former South Bend, Indiana, Mayor Pete Buttigieg won the caucuses with the eventual nominee and president, former Vice President Joe Biden, finishing a distant fourth. Biden would then finish fifth in New Hampshire a week later.
These dismal performances led to serious questions about Biden's candidacy at the time as he was previously seen as the front-runner among Democrats. It took the fourth nominating contest in South Carolina that year before Biden would win his first state and reclaim his front-runner status.
This led to Biden and other Democrats calling for significant changes to the calendar in future elections. Biden and some Democrats have argued that a state like South Carolina is more representative of the party's base.
Democrats have decided to still allow the tradition of in-person caucuses in January, but will now allow caucus voters to submit mail-in ballots in March. This effectively has moved the caucuses date to later in the nominating process.
Republicans have vowed to keep Iowa at the top of its nominating calendar.
