Mayor Luke Ravenstahl's proposals to sell the city's parking garages and slap a 1 percent tuition tax on the city's colleges are coming for one reason.

That would be the reason we in Pittsburgh generally look right past: The city's boundaries no longer jibe with the modern economy and it's hard to imagine they ever will again.

Back when the region's economic engines were steel and other manufacturing, and most people walked to work or took the trolley, this setup worked fine. Factories paid property taxes and business taxes. There was a sense that all were kicking in their fair share to pay for cops, firefighters, paving, snow removal, streetlights and such.

But now the region's economic engines are hospitals and universities, and they mostly don't pay property taxes. They don't pay city payroll taxes, either. Then you throw in the fact that we've spent most of the past century remaking our highways, often tearing down city neighborhoods to do so, to make it ever more convenient to flee the city when the workday ends.

Pennsylvanians are mostly living where they want to live, and where state and national policies have encouraged them to live. But that leaves Pittsburgh without a tax base.

Out West, cities have taken care of this by expanding. Houston went from 160 square miles in 1950 to roughly 600 square miles today, San Diego from 99 square miles to 324, Phoenix from 17 to 517. And so on.

Here, we've stuck to pretty much the same setup we've had since Sophie Masloff was leading cheers at Fifth Avenue High in the '30s. The city's footprint is just under 56 square miles, an early 20th-century political construct trying to operate in a 21st-century economy. People make their money in Pittsburgh and spend most of it outside, so now we have a mayor rattling his cup when college students walk by.

Each mayor, in his or her turn, comes up with ever more creative ways to deal with the reality that the economic model is broken. Mr. Ravenstahl's proposal may not even be legal; City Controller Michael Lamb, who has to certify the reasonableness of the city's revenue projections, says the Legislature "has made it pretty clear" it won't allow a tuition tax.

Many Pittsburghers can tell you that the city has lost more than half its population since 1950, but few among us fully grasp why that is. People moving away is only part of the answer. Smaller families is another. But the biggest reason is that civic borders have remained so rigid you'd think they were set on Mount Sinai.

Did you know that, even after losing more than half our population, Pittsburgh has more residents per square mile than five of the 10 largest cities in the United States? That's because those great, sprawling places out West aren't cities in the way we know them in Pennsylvania. They're built for cars, closer in size and residential texture to Allegheny County than to Pittsburgh proper.

We don't ever get around to real change. Instead, we see the unintentional comedy of college presidents banding together to decry a 1 percent tuition hike. If these folks ever managed to keep their annual tuition increases that low, students might throw a pep rally. A quick computer check of Pitt's in-state tuition shows that it has more than doubled in the past 10 years, catapulting from $6,424 to $13,344.

Bet your 401(k) can't match that bump.

The customary city-vs.-suburb debate is now in full swing, and might reach the boiling point if Mr. Ravenstahl is successful in leasing the Pittsburgh Parking Authority's garages. The mayor hopes a decades-long lease to a private operator would net $200 million to plunk into the city's pension fund, which at last count had only 31 percent of the $899 million it needs to pay benefits due retirees and current workers.

Parking rates would almost surely soar in private hands. The authority has kept fees slightly below the market rate to help Downtown property owners and merchants, but a private operator would have no interest beyond profits. Commuters' wallets would take the hit.

There's a similar story in every city in Pennsylvania. Hospitals and universities are the new regional economic engines, but the communities that host them inevitably have high levels of tax-exempt property. So most Pennsylvanians have learned to live close to, but not in, the cities. They can certainly be comfortable in the knowledge that nobody in Harrisburg has the brains or even the desire to change the status quo.

If there is change, it will have to come from the outside in, because political power is in the suburbs now. Pennsylvania has to figure out a fair way to have all metropolitan residents vote on the issues that affect them. The alternative is the current plan -- to keep pretending we're not a metropolitan area until it goes away.

Somebody could write a book about that.