The discussion of American manufacturing is often a muddled one, steeped in nostalgia for a bygone era and accompanied by a certain misty-eyed conviction that it is a sector in ceaseless decline. A new study from the McKinsey Global Institute adds some welcome clarity. In 184 pages, the global consulting giant presents a picture of manufacturing as among the most dynamic sectors of the U.S. and global economies, driving higher productivity and standards of living. But it also shows that what we usually think of as a traditional manufacturing job isn't coming back.