Today, in Sonoma County and across the country, postal carriers will make their rounds, walking and driving thousands of miles to deliver magazines, packages, bills, solicitations, even a few letters.

Six months from now, with or without congressional approval, the U.S. Postal Service says it will stop Saturday mail deliveries.

They will be missed, just as milk delivered to the doorstep and 50-cent gasoline are missed.

But times change, and the Postal Service must change to keep up with the times — and to stay in business.

Congress, customers and postal employee unions can stand in the way of change, but they can't hide the staggering losses that threaten the Postal Service, an agency older than the United States itself, with insolvency.

Since 2007, first-class mail volume has declined by 37 percent reflecting a shift from mailing checks to paying bills online and from letters to email and text messages. Despite regular rate increases, postal revenue has fallen 13 percent, and even aggressive cost-cutting hasn't been enough to make up the difference.

The Postal Service lost almost $30 billion over the past three years. Last fall, it defaulted on an $11.1 billion loan, and it's presently losing money at a rate of $25 million a day, with annual losses projected to reach $20 billion by 2016.

Working out this mess will take a lot more than ending Saturday mail delivery.

Still, it's a first step, offering savings up to $3 billion a year in fuel and staffing costs.

It also serves a larger goal: Maintaining universal mail delivery.

Overnight delivery and broadband Internet service have yet to reach many far-flung corners of America. With few people and long distances to major population centers, rural areas are of little interest to many private companies.

For small towns and other lightly populated areas, snail mail remains a vital link to the rest of the world.

It needs to be protected, but there's plenty of places to save money if the Postal Service can get past its major barriers — customers who want more services but object to higher rates and employees who hang on to excessive benefits including protection from layoffs.

No obstacle is bigger than Congress, which retained the ability to micromanage the Postal Service even after it became an independent agency, required to subsist on its revenue. As losses mounted, Congress ignored pleas to free postal officials from restrictions on rates and mandates including six-day service.

Postal officials say a loophole in a stopgap measure funding federal agencies allows them to halt Saturday mail delivery. Post offices will remain open, and packages will still be delivered, a nod to rising revenue from e-commerce.

Congress still could require Saturday delivery. Doing so would ignore polls showing overwhelming public support for five-day delivery if it saves money. It also would undermine one of the most common refrains in politics: that government must live within its means.

The Postal Service wants to take a step in that direction. Congress needs to get out of the way.