On a cold night in January nine years ago, Barack Obama won the Iowa caucuses. That first big step on the young senator's unlikely path to the White House was fueled by an army of campaign volunteers, which Obama later called one of his proudest legacies.
"That's what America needs right now," Obama told campaign workers a year later, after he was sworn in as president. "Active citizens like you, who are willing to turn towards each other, talk to people you've never met, and say, 'C'mon, let's go do this. Let's go change the world.' "
