Michael Nutter may become the first big-city mayor to be elected by a 12-year-old.

The 12-year-old would be Olivia, Nutter's daughter. Olivia starred in a fetching campaign ad that helped trigger her dad's come-from-behind surge, which culminated yesterday in an impressive win in Philadelphia's Democratic mayoral primary.

In this Democratic town, Nutter's victory makes him the prohibitive favorite to win the fall election over Republican Al Taubenberger.

Then, Nutter's job will be to worry day and night about 12-year-olds who don't have the same prospects in life as Olivia, the ones who attend the city's struggling schools, the ones who have to dodge bullets on its more dangerous streets, the ones who need their city to give them a reason to hope.

Nutter will come to that hard task with few illusions, and a decent grasp of what will be demanded of him. He won't be daunted. Uphill climbs suit him. Fourteen years on City Council have given him a mix of realism and optimism that many voters found attractive.

He wants to fight for a new Philadelphia, not preserve the old, creaky arrangements. But he differs from Tom Knox, the other candidate who campaigned for City Hall reform, in this way: Nutter is not a novice who spouts silly throw-the-bums-out rhetoric. Nutter knows that not every elected official is a crook, not every city worker a lazy hack.

Nutter won because he is smart and serious at a moment that demands smart and serious. He won because he worked hard, ignoring the scoffing sages of the old ways who told him he had no chance. He won in part because some of his opponents ran campaigns that will have political experts scratching their heads for years.

More than what Nutter's victory says about him, though, the biggest story may be what it says about Philadelphia. Here are several hopeful things that these election results say:

The city's residents have had it up to here with the venal same-old-same-old at City Hall. The top two finishers (Nutter and Knox), ran on promises to clean up the stable.

Race is not the alpha and omega of city politics. A black man won because he got a lot of white votes. White men got some black votes.

You can't just buy City Hall, even if you blow $10 million. Enough voters figured out the difference between TV Tom, the ethical crusader Knox pretended to be, and the cold schemer his business record showed him to be.

The city's new campaign finance laws work, despite all the carping. The candidate who followed the rules without whining ended up winning.

The Machine is creaky. The two candidates who counted more on old-fashioned politicking than on a message of reform - Bob Brady and Chaka Fattah - did worse than any political pro would have predicted on New Year's Day.

Substance and ideas matter. Philadelphians should be proud of the explosion of civic activism and dreaming that this election spawned. Citizens, to an unprecedented degree, decided what they wanted this election to be about and forced candidates to address their concerns. Do you really think, left to their own devices, that some of these guys would have ever raised issues like sustainable development, ethics reform, the creative economy or homelessness? Never.

Helped by campaign finance reform, foundations, the media and the Web, an aroused citizenry made its voice heard. Is it any wonder a wonk won?

This was, overall, a good campaign - despite some nasty stuff during its final, desperate days. Let's hope Nutter reaches out swiftly and graciously to the three opponents who will now return to important posts - congressmen Brady and Fattah, and state Rep. Dwight Evans.

If they all can recover swiftly from the bruises of the campaign, Philadelphia's interests could be represented by a most capable team.