My mother sent me this TedX video of David Autor, an MIT Professor of Economics. It's great. I highly recommend it. Here is his paper on the subject offering even more detail.
The impact of technology is all around us and just seems to accelerate leaving entire generations in lower-paid, less skilled jobs than they had only 30 years ago. This chart clearly shows waves of losses and gains in US employment by sector between 1940 and 2010.