WASHINGTON -- If you haven't looked lately, there has been a profound change in what's in your mailbox. It probably means those new 39-cent stamps you just bought won't have a very long life, maybe a year at best.

		Bill McAllister, Washington correspondent for Linn's Stamp News, is a former Washington Post reporter who has covered the U.S. Postal Service for almost 25 years (bmcallister@cox.net).

What is in the mail changed dramatically last year. It is a shift so important that postal officials have been warning that the result is almost certain to lead to higher stamp prices and more frequent rate changes.

What happened was that for the first time the number of advertising letters carried by the U.S. Postal Service outnumbered first-class mail.

Yes, the mail many Americans decry as "junk mail" has now become the majority of the mail delivered to most households. Letters from "Aunt Minnie," as the service calls single-piece first-class letters that carry a 39-cent stamp, are now the minority and declining steadily.

Because all that advertising mail -- the Postal Service prefers to call it "standard mail" -- is delivered at a price far cheaper than your 39-cent letter, the change has far-reaching implications for the future of a federal agency that is older than the Constitution and has more civilian workers than the Pentagon.

Simply put, the problem is that it takes about 2.5 advertising letters to make up the contribution to the Postal Service's staggering overhead costs that one first-class letter makes. That's why postal officials already are at work on their next rate increase, one likely to be filed with the independent Postal Rate Commission this spring and become effective early next year.

Gene Del Polito, president of the Association for Postal Commerce, says that case promises to be "the mother of all rate cases" as the Postal Service attempts to shift more of its $70-billion-a-year costs to the big mailers who compose Mr. Del Polito's organization.

What's likely to happen is a 10-month battle before the rate commission as mailers fight over which class of mail will have to pick up the tab that first-class letters no longer can bear.

That battle is likely to ring with cries of "death spiral" as mailers attempt to fend off increases that they argue will only drive down mail volume more quickly and place the U.S. Postal Service's future in an even more perilous state.

You don't have to be the nation's postmaster general to realize, as a commission appointed by President Bush discovered nearly three years ago, that the Postal Service is facing a crisis unlike anything it has known since its founding in 1775 by the Second Continental Congress.

"Absent fundamental reforms, the risk of a significant taxpayer bailout or dramatic postage rate increases loom large," declared the President's Commission on the U.S. Postal Service.

Mail volume is likely to continue to decline, said the panel. The big agency's costs, most of them directly linked to 700,000 employees who handle the mail, will continue to soar.

Unless Congress acts, the bipartisan commission warned President Bush that the Postal Service faces three possible fates. It could "dramatically roll back service, seek a rate increase of unprecedented scale," or seek "a significant taxpayer bailout."

As bleak as the commission's warnings to President Bush, what's surprising is that Congress has failed to address the issue. Legislation that would allow the Postal Service to impose higher stamp prices more quickly has cleared the House, but has been stalled in the Senate.

The legislation would give the service some financial relief, by allowing taxpayers to pay some pension costs of postal workers who served in the military and relieving the service of maintaining a large escrow fund. Postmaster General John E. "Jack" Potter has blamed the recent 2-cent rate increase entirely on the escrow account provision, which requires the service to salt away money to cover the soaring health costs of its retirees.

Even if the House-passed postal bill clears the Senate, the White House is threatening to veto the measure because of its costs. The Postal Service itself doesn't like the reform measure either, arguing it gives too much authority to what would be a postal regulatory authority.

In the meantime, under pressure from mailers, Congress and the Governmental Accountability Office, the service has begun its long-promised review of the more than 300 mail-processing plants that the service runs. The network grew haphazardly in an era of constantly growing letter volume, but it now has far more capacity than the service has letters.

With postal executives recognizing that letter volume may have peaked and with newer sorting machines capable of handling the work with fewer employees, the agency has begun what it hopes will be an intricate dance to downsize without having to lay off workers or upsetting Congress.

Thus far, none of the more than 50 mail-sorting "consolidations" being studied have been opposed by Congress. Some communities, like Olympia, Wash., and Rockford, Ill., are troubled that the changes could deny their cities its own postmark. (Some sorting operations would be moved from the Greensburg Post Office to the Pittsburgh mail processing plant.)

As traumatic as these changes may be, Robert McLean, executive director of The Mailer's Council, an umbrella group of many large mailers says, "Some would say that these are the easy steps."

What lies ahead promises to be even more difficult as the Postal Service becomes more an advertising medium and less a primary communications service.

Ever since Richard Nixon kicked the old Post Office Department out of his Cabinet in 1971, the Postal Service has been something of a big, unwanted chunk of the federal bureaucracy. Charged with making it on its own, without the direct support of federal taxpayers, the agency has stumbled from rate increase to rate increase.

The huge agency has never had an advocate with a pulpit as big as its problems.

Mr. Potter, a career postal worker and the nation's 72nd postmaster general, has been amazingly successful in squeezing savings out of what remains a massive bureaucracy and the only part of the federal government that claims to touch every household, every day.

Even the postmaster general knows that there are limits to how much he can save by rearranging where letters are cancelled or delaying construction of new post offices.

Whatever he does to change the agency's structure, he knows those changes alone won't bring back the missing letters.