U.S. manufacturing jobs must come back (pp. 20-21 of the link):

Manufacturing is key to long-run prosperity because it is a major center of productivity growth and innovation. When U.S. manufacturing moves offshore, associated R&D can move too, thereby further diminishing future innovations at home. Another problem is that international trade remains concentrated in goods. This means that, over the long haul, countries need to be able to produce and sell manufactured goods in order to finance imports. The erosion of U.S. manufacturing capacity undermines this ability, potentially risking a future decline in U.S. living standards . . .

And we know basically what has been happening for a helluva long time: other countries have been helping their manufacturing industries, manipulating their exchange rates, and/or under-paying their workers, while the U.S. has been sucking money out of domestic industry and putting it into financial speculation and overseas investment. These (obviously) have made our manufacturing industries uncompetitive:

U.S. consumers buy imports rather than American-made goods because imports are cheaper. This price advantage is often due to under-valued exchange rates in places like China and Japan, which often swamps U.S. manufacturing efficiency advantages.

Under-valued exchange rates are only one of the policies countries use to boost exports and restrain imports, so that they run trade surpluses while their trading partners (including the U.S.) run deficits. Other policies for export-led growth include export subsidies and barriers to imports.

In the modern era of globalization export-led growth is supplemented by policies to attract foreign direct investment (FDI), a pairing that has been particularly successful in China. Such FDI policies include investment subsidies, tax abatements, and exemptions from domestic regulation and laws.

These policies encourage corporations to shift production to developing countries, which gain modern production capacity. This increases developing country exports and reduces their import demand. Meanwhile, corporations reduce home country manufacturing capacity and investment, which reduces home country exports while increasing imports.