On February 10, 2007, Barack Obama stood before the Illinois capital building and announced his potentially historic presidential bid. The next day, he was in Iowa Falls, campaigning. He was far from the first-Hillary Rodham Clinton, John Edwards, John McCain, and Mitt Romney were already swarming the Hawkeye State, seeking votes behind every hay bale. Why Iowa? After all, in the lead-up to the 2008 presidential primary, both Iowa...