Take a look at the map here. Sen. Barack Obama won the city by a huge margin in Tuesday's primary with a coalition Pittsburgh hasn't seen in a while.

That map didn't matter much Tuesday. Sen. Hillary Clinton still won by about 9 percentage points statewide and in Allegheny County. The Obama coalition hereabouts stretched from Fox Chapel to Braddock but didn't get enough points in between, either on the county map or in terms of voters' income.

But as the city's political junkies look toward yet another mayoral race in the spring of 2009, this map has intriguing brush strokes. Consider:

• Mayor Luke Ravenstahl's home turf, the North Side, did not go for his favored candidate, Mrs. Clinton. About 62 percent of North Side voters went for Mr. Obama, slightly greater than his 59 percent slice in the city as a whole.

• In the November 2007 mayoral election, Mr. Ravenstahl's greatest support came in largely black wards. Those places had little interest in Republican challenger Mark DeSantis, but those same wards lined up Tuesday with the prosperous East End, about the only area Mr. DeSantis carried last fall.

• It seems every prominent mayoral critic and/or potential challenger is an Obama supporter: Councilmen Bill Peduto, Doug Shields, Ricky Burgess and Patrick Dowd and City Controller Michael Lamb, to name a few. Being on Mr. Obama's side this year may be helpful in the city's black wards during next year's Democratic primary.

On the other hand, this presidential primary is in many ways unique, with no likely carryover. College students helped make Tuesday's turnout about 20,000 voters more than the November 2007 mayoral election's. Even if many of these newly galvanized voters gave a rip who Pittsburgh's mayor is, many dorms will be cleared out by the time next May's primary rolls around.

That said, Mr. Peduto thinks this kind of coalition could swing the mayor's race.

"It isn't uncommon for young or more progressive areas to team up with the African-American community in supporting a [mayoral] candidate,'' he said.

Mayors Richard Caliguiri and Sophie Masloff both succeeded with such coalitions, Mr. Peduto said, "but we haven't seen it since then. We did see it with Obama.''

Highland Park, Squirrel Hill and Shadyside, where Mr. Obama prevailed, could easily unite behind the right progressive candidate, he said.

Mr. Dowd, so new to council that the paint has barely dried in his office, was an early Obama supporter. He has a slightly different view.

"I don't think you can look at [Obama's] numbers and think those translate to other people,'' he said.

Democratic voters Tuesday were eager to make history, casting votes either for a woman or a black man. Mr. Obama has shown that a compelling candidate can make a grass-roots campaign work, but he's "one of the most amazing candidates we've ever seen.''

Rev. Burgess, another council freshman, made a similar point. The Obama campaign represented "a confluence of Democratic voters wanting change and a truly dynamic, unifying candidate.'' He took more than 80 percent of the vote in the council's two predominantly black districts. But what makes him "a phenomenon'' is taking the North Side, where two-thirds of voting-age residents are white, and the affluent East End.

Whether that is a stand-alone moment, Mr. Burgess said, "depends on having a candidate who can build a similar coalition and whether or not such a candidate exists and what that candidate stands for.''