Online competition and health care costs threaten to do what "neither rain, nor sleet nor gloom of night" has accomplished.
The U.S. Postal Service - whose workers brave the aforementioned elements to complete "their appointed rounds" - is tempest-tossed in red ink.
The agency lost $16 billion last year. That's a lot of money to recoup one "Forever" stamp at a time.
The postal service is a constitutional creation that seems assembled from diverse elements of governing. It is an independent agency of the federal government, but receives little direct taxpayer assistance. In addition, it must ask Congress - pardon the pun - for its stamp of approval to change operations.
But change it must to avert an additional $15 billion in losses anticipated this year.
Those losses are attributed to competition - including online bill payments - and a congressional requirement that it make advance payments to cover health care costs, more than $11 billion last year, for future retirees - a requirement that no other federal agency, including Congress itself, faces.
As always, reducing a shortfall means cutting expenses or raising revenue.
Proposals to cut expenses include eliminating Saturday delivery and phasing out door-to-door delivery.
A relatively new revenue-raising idea being floated by Postmaster General Patrick Donahoe would permit the U.S. Postal Service to deliver alcoholic beverages. The practice now is prohibited.
"There's a lot of money to be made in beer, wine and spirits," Donahoe said, citing wine shipments by tourists. "We'd like to be in that businesses."
How much is a lot?
Donahoe estimates up to $50 million annually.
That's a long way from $15 billion, but the concept raises some important considerations about the future of the U.S. Postal Service.
As a creature of the Constitution, the agency is not eliminated easily.
But if Congress leaves it at a competitive disadvantage, how long before it succumbs to insolvency and self-destructs?