Those wars left a political toll in the Democratic Party, too. John Kerry's support for the war in Iraq hobbled his efforts to draw a clear contrast with Bush; similarly, Hillary Clinton's support for it gave Obama, a junior senator from Illinois, a shot at challenging the party's reigning dynasty.
Obama's message of "hope" and "change" was appealing to a nation that had grown sick of the political paralysis of the past 15 years. And when the economy cratered in the last months of Bush's tenure, Obama was there to pick up the pieces.
Through it all, the nation was left basically where it was at the decade's start -- closely divided, and unsure of what's next.