The announcement that 110 workers at Chattanooga's Shallowford Road Mail Processing and Distribution Center will be transferred or laid off sometime after mid-May highlights the painful but inescapable fact that the Postal Service has grown less useful to many Americans.

The closing of the Chattanooga facility is one of hundreds announced Thursday. Nationwide, closings and consolidations will mean the loss of about 35,000 jobs, postal officials said, though many are expected to come through attrition, not layoffs.

No one delights in job losses, but the Postal Service cannot keep operating at current staffing levels when demand for its services has plunged.

How grave is the agency's financial condition? On its current trajectory, it expects to be losing up to $18.2 billion per year by 2015.

Much of that is due to the fact that millions of Americans every year are turning to the Internet for bill paying and routine correspondence. It's fast and doesn't require the cumbersome use of stamps and envelopes.

Given those advantages, there is no reason to think Americans in large numbers are going to return to traditional mail -- particularly when the agency is looking at raising stamp prices over time by up to 5 cents and eliminating Saturday delivery, which will make its services even more expensive and less convenient.

It's true the Constitution let the federal government establish the Postal Service: "The Congress shall have Power ... to establish Post Offices and Post Roads," Article I says.

But the Constitution does not mandate post offices -- much less require the Postal Service to have staffing levels that disregard actual market demand. So as troubling as job losses and facilities closings are, there simply appears to be no option.