Project Syndicate: J. Bradford DeLong: Where US Manufacturing Jobs Really Went: In the two decades from 1979 to 1999, the number of manufacturing jobs in the United States drifted downward, from 19 million to 17 million. But over the next decade, between 1999 and 2009, the number plummeted to 12 million. That more dramatic decline has given rise to the idea that the US economy suddenly stopped working–at least for blue-collar males–at the turn of the century…