As the first state to select delegates in Election 2008, the Iowa caucuses are understandably considered very important in the presidential nomination process. The caucuses present an opportunity for national frontrunners to solidify their lead as well as underdogs in national polls to gain momentum heading into New Hampshire and the Super Tuesdays thereafter.

But how predictive have the Iowa caucuses been in determining the eventual presidential nominee? An examination of contested party caucuses—that is, election years in which a sitting president is not seeking re-election—reveals the winner of the caucuses go on to secure the nomination just shy of half the time. However, the caucuses have been increasingly predictive in recent years.

On the Democratic side, since 1972 the eventual nominee has won 3 of the 7 such caucuses: John Kerry (2004), Al Gore (2000), and Walter Mondale (1984). In 1972 George McGovern lost by 13 points to Edmund Muskie, in 1988 Michael Dukakis finished in third place (9 points behind Dick Gephardt), and in 1992 Bill Clinton finished in third place (73 points behind Iowa native Senator Tom Harkin). In 1976 Jimmy Carter (28 percent) was the leading candidate, though “Uncommitted” caucus-goers totaled 37 percent of the total vote.

On the Republican side, the eventual nominee has won 2 of the 4 caucuses since 1972 in which sitting presidents were not running: George W. Bush (2000) and Bob Dole (1996). In 1988 George H.W. Bush placed third (18 points behind Dole), and in 1980 Ronald Reagan finished in second place (2 points behind George H. W. Bush).

From Bob Dole (1996), to Al Gore (2000), to George W. Bush (2000), to John Kerry (2004), the current trend favors those candidates who seize first place in Iowa to eventually win the nomination. No doubt this trend is partially due to some correlation (e.g. those candidates who have been successful in raising money before the Iowa caucuses tend to do well there and in the primaries thereafter) as well as causation (the Iowa bounce has undeniably helped some candidates—such as Kerry in 2004, who had previously been trailing Howard Dean in New Hampshire).