After the 1968 Democratic National Convention protest activity, Democratic Party leaders decided to make changes to their presidential nomination process by spreading out the schedule in each state. Because Iowa had a complex process of precinct caucuses, county conventions, district conventions, and a state convention, they chose to start early. In 1972, Iowa was the first state to hold its Democratic caucus, and it had the first Republican caucus four years later.[14]
Under Iowa law, political parties are required to hold caucuses every two years to select delegates to county conventions and party committees.[2]
For Republicans, the Iowa caucus used to follow the Iowa Straw Poll in August of the preceding year. The Iowa Straw Poll was held six times, beginning in 1979, but only three Straw Poll winners went on to win the caucus the following year. The Straw Poll was discontinued in June 2015.
Iowa Democrats will be voting for their primary candidate via mail in ballots through March 15 which is Super Tuesday.
Since 1972, the Iowa caucus has successfully predicted the winning Republican candidate 43% of the time (of which three were uncontested races - Reagan in 1984, George H.W. Bush in 1992, and George W. Bush in 2004) while they have successfully predicted the Democrat candidate 55% of the time (with Bill Clinton and Barak Obama running unopposed) - so essentially its a 50/50 chance that former President Trump will go on to win the party's nomination.
On to New Hampshire for the Republican candidates, while the first Democratic primary will be the day after Groundhog's Day in South Carolina, where six more weeks of winter doesn't matter.