The Atlantic Monthly has an excellent article on the future of manufacturing in the United States, which is also something of a meditation on declining opportunities for workers with low and moderate skill levels:

This may be the worst impact of the disappearance of manufacturing work. In older factories and, before them, on the farm, there were opportunities for almost everybody: the bright and the slow, the sociable and the awkward, the people with children and those without. All came to work unskilled, at first, and then slowly learned things, on the job, that made them more valuable. Especially in the mid-20th century, as manufacturing employment was rocketing toward its zenith, mistakes and disadvantages in childhood and adolescence did not foreclose adult opportunity.

For most of U.S. history, most people had a slow and steady wind at their back, a combination of economic forces that didnt make life easy but gave many of us little pushes forward that allowed us to earn a bit more every year. Over a lifetime, it all added up to a better sort of life than the one we were born into. That wind seems to be dying for a lot of Americans. What the country will be like without it is not quite clear.