In the midst of an otherwise-familiar piece in the Jackson Clarion-Ledger about the return of protectionism — it’s been “returning” for quite some time now — were these arresting statistics:

In 1943 and 1944, with factories working overtime to build the ships, tanks and planes needed to fight World War II, manufacturing accounted for four of 10 jobs in the U.S. That was the peak; manufacturing has been declining ever since. Manufacturing now accounts for one job in 10 in the nonfarm work force. The declines have been particularly painful in the industrial Midwest and rural South, which have been battered by competition from China.
“China has just exploded on the global scene since 2002. Every economy on the planet has lost jobs to China,” says Mark Zandi, chief economist at Moody’s Economy.com, an economic forecasting company.
A Moody’s analysis found 16 percent of the nation’s 379 metropolitan areas are in recession, reflecting primarily the troubles in manufacturing. There have been heavy job losses in a variety of industries from textiles and apparel to paper and furniture.

Those mystified by the continued political valence of protectionism should keep this last number in mind: 16 percent of metros in recession. National economic data are averages. Though the American economy as a whole remains strong, there are pockets of significant joblessness and decay. They are political constituencies primed for demagoguery about international markets for products, capital, and labor.