The Post has an article on "The New American Voter". In 1960 political scientists wrote "The American Voter", an exhaustive analysis of the knowledge and characteristics of the voters. Now the subject has been revisited, using the same methodology. (Short summary: Americans are as uninformed about political issues today as they were 48 years ago.)
But, as Libby Copeland writes: "(They had to eliminate the chapter on the agrarian vote, though, because there aren't enough farmers left anymore for a usable sample.)"