They Know How to Caucus

The WaPost has an especially good (and long) profile on the history (and future) of the Iowa caucuses:

The battle for the best political talent takes place nationwide every election cycle, but nowhere is it fought as fiercely as in Iowa. Victory in the caucuses held here in January every four years has traditionally been seen as critical in generating what President George H.W. Bush once called the "Big Mo," and the elite group of strategists experienced in producing it are seduced and fought over.