I need to confess something. Five months ago, I couldn't stand Barack Obama.
During the primaries I was rooting for Hillary. Partly this was because of her character and intelligence, but mostly it was simply because I have rose-tinted memories of the last president who wasn't chronically incompetent. From that point of view, Obama was an irritant: an upstart who clearly didn't have enough experience for the job, and whose name was too funny and whose skin too dark to win an election.
Once he got the nomination, I fell in line, if only because of a heartfelt desire to see the Republicans suffer for eight years of incompetence, ignorance and greed. (You know Sarah Palin thinks Africa is a country, by the way? True story.) And as I learnt more about his biography, his policies, his intellect, I began to come round to the idea that Barack Obama might just do a good job of this.
But any lingering doubt I had about whether he was the right choice would have been erased by a conversation I had two weeks ago in Pennsylvania.
When we pulled into a gas station in Erie, Luther, its elderly black owner, was hunched over three huge boxes stuffing envelopes. His eyes unaccountably brightened when I told him I was a British journalist.
'You wouldn't be the journalist who wrote that piece saying that Americans should vote for Obama to show how much progress they've made, would you?' he asked. I wouldn't. Boris Johnson would. Luther had photocopied the mayor's Obama endorsement two hundred times and was sending it to everyone he could think of. Because he wanted to believe the claim that - with hard work and intelligence and perseverance - his grandchildren had as much of a chance of being president as the white kids next door.
Because for the first time, being black didn't exclude him from the American dream.
President Obama will inevitably prove a disappointment. No one could live up to the huge expectations placed on him, and in six months time the thousands of t-shirts bearing his face will be completely unwearable. (What, after all, could be less cool than to go round with a sitting world leader on your chest while he ducks questions about the budget deficit?)
But his campaign promised change, and it promised hope. And if he achieves nothing else, he's already delivered those.