In the mist of an extremely long presidential primary and campaign - as long or longer than I can remember - conversations always reach this question: "Who cares about Iowa?" Obviously campaign fatigue has already hit 10 months out from the general election. But it's an interesting question. After providing an answer I'm not confident that I've even convinced myself that Iowa matters. The media give it an extremely significant place in presidential campaigns, but winners of the Iowa caucus don't always win the nomination. So does Iowa have a significant effect? David Redlawsk, Caroline Tolbert, and Todd Donovan's relatively new book, Why Iowa?: How Caucuses and Sequential Elections Improve the Presidential Nominating Process (2009), analyzes the Iowa caucuses. Here's an excerpt:
How Iowa "matters" may be determined, at least in part, by how voters and the news media assess whether or not candidates meet or exceed expectations there. The news media appears to use results from Iowa to determine whether candidates deserve its increased or decresed coverage in later states. Voters in these states may form evaluations about candidate viability and electability based on results from the early states, such as Iowa and New Hampshire. Using aggregate election results data from 1976 through 2008, we find that changes in media attention given candidates that are associated with outcomes in Iowa affect candidate performance in the New Hampshire primary. Futher, similar shifts in media attention due to results in New Hampshire help predict a candidate's overall vote share across all primaries (142).
The book goes into much more depth about the process, caucus behavior, and Iowa's reverberating affect on subsequent primaries.