There was a map of the United States produced after the 2000 and 2004 elections, showing the presidential campaign victories on a county-by-county basis in blue and red. America was a sea of red, with clusters of blue for the most part relegated to major urban areas in the East, West, and scattered in between. The Democratic Party is an urban one, focused largely on urban problems and constituencies. But in order to win in 2008, Democratic leaders knew that they needed to woo small-town America. The time was ripe, the theory went, with an unpopular president, an unpopular Congress,...