On Election Day 2006, American voters did almost exactly what history would predict: giving a president in the sixth year of his administration a serious smackdown, as an electorate wary of politicians and parties hedged its bets and chose a divided government. Since World War II, the parties that controlled the White House for two terms have lost an average of 29 House seats and six Senate seats in their second midterm elections. This election fits tidily into that pattern. President Bush bucked another ubiquitous trap of modern presidents when he actually picked up Congressional seats for his party in...