"Wasteland" actually refers to this accurately. It's used all the time in apocalyptic fiction, to refer to the world in general, ie the barren landscapes out away from (what used to be) civilization, and while it is sometimes used to describe the ruined cities, such as "Capitol Wasteland" in Fallout 3, that's incorrect, as they're something else. But in that genre, it's almost, kind of, an acceptable break from reality, because of the genre's trappings. You shouldn't though.
"Population: one" is often thrown around in stories where a loner lives or comes across a place that's abandoned. (that gives me an idea for a lone character's abode...)
Related to wastelands: you can also have "cultural" or "moral" wastelands. Not strictly speaking ruined cities and desolate wastes, but rather a culture that doesn't have culture, or morals, or anything that consensus agrees is "good and wholesome". Like hookup culture, as seen negatively by traditionalist hopeless-romantic types.
"Graveyard" or "junk yard" may be applicable.
"Population bankrupt" just came to me. Not sure that's any good, though...
In Australia, we refer to middle-of-nowhere places by names like "The Boonies" or "Whoop Whoop" which just sounds silly, but it's what the natives call them, so it's very insensitive to devalue the native population. ("Colonialism is bad" was the thrust of many of my cultural studies classes in college). "Out in the sticks" is Australian, but could very well work in the more desert-ly places in America. Mexico of course has it's own connotations, but we're kinda like it in a way to many Americans and English (or at least we all like to joke that it is).