Chris Briem figures Bob O'Connor showed he knew his customers pretty well last year when he handed out pillboxes as campaign souvenirs during the Pittsburgh mayor's race.

More than half of those who made their way to polling places in last May's primary election, when Mr. O'Connor won the Democratic nomination, were 54 or older. In several city wards, the median age of voters was older than 60, and there wasn't a single ward in which it was younger than 50.

The picture for the county as a whole was much the same. The oldest median age for any municipality was in Aleppo -- 68.5 -- one of 14 communities in which the median age of voters was 60 or older.

The relative youngsters among the county's municipalities were Pennsbury Village, 49.6; and Trafford, 47.8. Every other community in the county had a median in the 50s.

Allegheny County's population is one of the oldest in the nation, with a median age of 39.6, according to the 2000 census, and the median age of voters who cast ballots in recent elections was older still, perhaps the oldest in the nation.

Mr. Briem's research quantifies the extent to which older voters dominate vote totals in the city and Allegheny County, most notably in primary elections, which typically attract a lower turnout. That demographic reality has significant implications for the way campaigns are conducted and for the policies the winners of those campaigns pursue.

From property tax rebates to prescription drugs to mass transit, city and state lawmakers have shown their willingness to spend tax dollars on programs that benefit seniors. The same dynamic exists on the federal level with a disproportionate share of domestic spending devoted to programs, notably Medicare, geared toward the elderly

The local numbers highlighted by Mr. Briem might be a harbinger of how the electoral pressure by and for the elderly can be expected to increase at the national level in the years to come. He said Pittsburgh, in the wake of the collapse of its manufacturing sector, became one of the oldest communities in the country over the past three decades. (Several south Florida counties have overall populations that are similarly elderly.) Mr. Briem said his guess was that Allegheny County's actual voting population is still older, however, because Florida's older demographic is based largely on such as snowbird migrants who may retain ties elsewhere. To a much greater extent, Western Pennsylvania's elderly people aged in place.

"To me, this is important data for what it says about the rest of the country," Mr. Briem said, referring to the continuing aging of the baby boom generation. "Our age demographic is what the rest of the country is going to see years down the road. I don't think people fully appreciate how dominant this [voting] age demographic is going to become."

The data that Mr. Briem culled from Allegheny County voter files also show that the much larger turnout in the 2004 presidential election produced a lower median age for voters, 46.8 for the city of Pittsburgh, for example, compared with 54.6 in the lower-turnout primary. In contrast to last year's primary, the median age of the presidential voters was close to the median for the total voting age population of the county, which, according to Mr. Briem's analysis, is approximately 47.

For the most part, a comparison of the two elections, the spring 2005 primary and the November 2004 general, shows a consistently younger median age for the presidential contest. For a large plurality of municipalities, however, the median voting age remained somewhere in the 50s, although more than a third of the county's 130 municipalities produced median voting ages in the 40s.

"There's never been any doubt that the elderly are the most powerful lobbying bloc in the country, and this just shows you why," said Morton Coleman, former director of the University of Pittsburgh's Institute of Politics. "That's why property tax issues loom so large. ... Even if you look at national government, something like 80 percent of domestic expenditures go to people over 65. ... That's not an accident.''

The age difference between last year's primary and the Bush-Kerry contest, in which both sides staged major get-out-the-vote efforts, was dramatic in a few areas.

In Pittsburgh's 1st Ward, which includes the neighborhoods around Duquesne University, the median voting age was 21 in the presidential year, but 54.4 in the subsequent primary. In the 4th Ward, which includes the University of Pittsburgh and Carlow University, the age gap was even wider, 24.3 in the 2004 general election and 62.7 in the 2005 primary.

"That does say an important thing," Mr. Coleman said. "Young people seem not at all interested in local politics."

Although City Council this year changed the date of a special election for the council district that covers Pitt to take place while school was in session, the turnout remained anemic.

"If you want to project yourself as an energetic young city, you want to encourage young voters' participation," Mr. Coleman said. "You have all these young groups like [the Pittsburgh Urban Magnet Project], but it's not transferring to local politics."

Mr. Briem said, however, that if the median voting age skews old now, it was almost certainly older in years past.

"The elderly population in the county and region actually peaked a decade ago, between 1995 and 1996," he said. "In both absolute numbers and proportion, the elderly population has been declining for a decade."