For decades now, the U.S. Postal Service (USPS) has been an icon of America’s lesser-hailed “can’t-do” spirit: unable to keep up with changing consumer trends, new technologies, a warming planet or a deepening economic crisis. For all their sensitivity to questions of environmental impact and cost, the USPS leadership in recent years might as well have given Hummers to their mail carriers to make their appointed rounds. As it turns out, the USPS and Hummer’s parent company, General Motors, have a lot in common these days. Both are currently generating multibillion-dollar annual losses, pushing products that ever fewer people want, burdening themselves with bloated payrolls and huge fixed-cost infrastructures, continuing to roll up enormous, unfunded pension obligations, and contending with some of the largest and most powerful labor unions on earth. Both, too, are expecting the American taxpayer to bail them out.

There are also some differences. We all know what an American automobile company is: a private corporation (or at least it was until recently). But almost no one knows what the USPS is. It’s easy to forgive that ignorance, however, and here is why.

The USPS is the successor to what used to be a full-fledged government department: namely, the Post Office Department, founded in 1792. It was so much a part of government that the Founders mentioned the rationale for it in the Constitution, and the Postmaster General was in the line of succession to the Presidency—last in line, yes, but in line all the same. So things remained until President Richard M. Nixon’s Administration reorganized the Post Office Department in 1970 in response to a debilitating strike by postal workers, establishing the newly branded USPS as a “corporation-like” independent agency. What did, and does, this mean?