This has been a situation decades in the making. As a nation, we have slowed our own industries. Our agricultural industry, once the envy of the world, has changed dramatically. At the turn of the 20th century, over 40% of Americans were employed by farms. Today, it is less than 1%. Our farms are producing more, but employ fewer people due to being run by corporations and advaced machinery.
http://www.ers.usda.gov/publications/eib3/eib3.htm
The story is the same for the steel industry, with once proud steel towns seeing some of the highest unemployment in the nation.
http://en.citizendium.org/wiki/Steel_industry,_history
We have given our industrial bases away to other countries. They produce products at cheaper prices which allow the corporations to make more money. Unions once served a purpose, protecting workers from intolerable work place conditions. Today, they only serve to raise production costs to the level that we price ourselves out of business.
With Congress giving up their responsibility of negotiating trade with foreign countries, corporations and lobbyists have been successful in getting trade agreements signed which eventually sent employment overseas. The best example being NAFTA. It was signed by Bush the Elder but passed into law under Clinton who hailed it as his greatest achievement.
We have been the authors of our own decline for a long time.