According to Data Mine, the U.S. share of global manufacturing value has been on a fairly steady decline since 2000 as Chinese manufacturing has shot up, surpassing Germany in 1999 and Japan in 2007.

The decline of US manufacturing is relative.  US manufacturing, on an absolute basis, is still growing.  However, this is not the case for the manufacturing employment.  More than one-third of American million manufacturing jobs disappeared between 1970 and 2010, while the Chinese now enjoy a total labor force five times that in the U.S.

Combining the two facts above, one can conclude that the growth of US manufacturing has relied on shedding domestic labor (incl. shifting manufacturing to China), and increasing productivity.