No doubt, the "computer glitch" that caused Delta Air Lines to shut down for six hours on Monday morning, canceling some 300 scheduled flights, was a great inconvenience to many summer travelers: People make plans based on estimated times of arrival; connecting flights require a combination of luck and precision. When a flight is cancelled, it usually means that the traveler must wait several extra hours, perhaps even a day, before arriving at his destination. And of course, it's no fun being marooned in an airport, or an airport hotel, in yesterday's clothes.

And so it was that, when National Public Radio found a stranded Delta customer to illustrate this vexing story, it settled on a woman whose voyage from Detroit to New Orleans had been delayed for nearly a day. Indeed, not only was she unable to return to her home until several hours later than she had planned, but her re-scheduled flight would deposit her at her destination sometime past midnight.

In the absence of any further details about the traveler's predicament, I am sympathetic—up to a point. I also tend to be sympathetic about stories of the shortcomings of the Postal Service. Until, that is, I consider the implications of putting an envelope in a mailbox in Washington, D.C.—one of millions upon millions such envelopes, emblazoned with a handwritten name and street address, city and state—and expecting it to arrive in a couple of days at a particular house on a street in a neighborhood of a subdivision in the northwestern suburbs of, say, a city in the middle of Texas.

The distance from Detroit, Michigan to New Orleans, Louisiana is a little over a thousand miles. As recently as a generation ago, it would not have been possible to choose any number of daily two-hour airplane flights between the edge of Lake Erie and a city at the mouth of the Mississippi River. A century ago there would have been no flights whatsoever, and a voyage by train would have meant a couple of days and a change of locomotives in, say, Chicago or Memphis. A century before that, and we're talking about weeks of perilous travel across desolate land and slow-moving water.

Indeed, if you draw a line representing the distance from Detroit to New Orleans westward from the east coast, it will take you well beyond the Appalachian range, which hemmed in English colonists for two centuries, to the shores of the aforementioned Mississippi. Up until comparatively recently, even such a journey by automobile would have been punctuated by narrow roads, punctured tires, unbypassed cities, sleepy motels, and malfunctioning carburetors.

The cancellation of a flight from Detroit to New Orleans, and its attendant inconvenience, is one way of measuring the distances we've traveled. This is small consolation, to be sure, for missed appointments, midnight cab rides or shortened vacations. But convenience has a useful relation to perspective.