Yes, The Atlantic had its "One Graph" explanation today, showing that Postal Service volume and revenue were going down in the email/PDF age. I will assume that you have already read that.
But if you would like to understand why the USPS has not been able to adapt to these trends, please read, right now, John Tierney's new article in Salon (plus one earlier today by Annie-Rose Strasser in ThinkProgress). Here is the headline on Tierney's item, which makes the main point:
Here's his argument in brief: Of course the Postal Service has needed to change everything it does because of the electronic revolution. But it is in such serious trouble not because it has resisted progress but because of a series of burdens imposed on it by Congress. One of them is laid out in Strasser's item: that the USPS, unlike any other organization private or public, is required to pre-fund 75 years' worth of pensions for employees it has not even yet hired. Without that requirement, it would still be showing a surplus.
Tierney makes the broader point that Congress' series of conflicting mandates to the Postal Service have put it in an impossible situation -- and a situation that some hybrid of Steve Jobs, Warren Buffett, Eric Schmidt, and Sheryl Sandberg would not have been able to solve. A sample of his case:
For decades, postal executives, looking ahead at trend lines that portended financial ruin, have tried to take steps that would put the mail system on a more sustainable footing. They've tried, for example, to pare down the enormous network of tens of thousands of post offices. But when they try to shut down costly, inefficient little post offices at rural crossroads, the local congressperson rises up in indignation, a defender of the local community's "heartbeat."...How does John Tierney know about any of this? He is actually an academic expert on the postal service, having written a standard text back in the 1980s. Atlantic readers will be familiar with his byline as a Correspondent for this site, where he has written mainly about about the modern realities of teaching. This is the place for me to note that I've been familiar with his work since long before he began writing here, since he is married to my sister.
We see in the case of the Postal Service an example of the larger problem of American democracy: members of Congress are so fixated on getting re-elected that rather than serving the will of broad popular majorities, they pay attention to, and heed the wishes of, well organized interest groups that represent tiny minorities of the population.
This is true across the board, on issues as diverse as gun control, farm subsidies, and postal services. To put it baldly, Congress is full of cowards - politicians whose calculus is based on the intensity factor: they cravenly give in to those constituencies or groups that care most intensely about a policy (usually those who benefit from it), and blithely impose costs on the broader public whose members are less attentive or aware of how they're being screwed.
But neither family connections nor Atlantic-team loyalty constitutes the main bias I bring to this topic. As I've mentioned before, the local Post Office was my first serious paying job, and I have long viewed the postal service in the positive light in which Benjamin Franklin originally cast it: as a public good and important part of the connective fiber of the nation. I hate the casual slurs against "snail mail," the assumption that its employees are all loafers [though some are], or the idea that blue-uniformed postal workers symbolize the sluggish Old Economy that a modern America is leaving behind.
The Postal Service has terrible problems, but like so many of our other disorders these are (as John Tierney points out) reflections of political collapse more generally. Read his article, and Strasser's. And consider saying something nice to the next letter carrier or postal clerk you see.