If you look at the share of manufacturing in total employment, the steady decline has been ongoing for decades

From the Federal Reserve Bank of St. Louis Blog.

"Many have complained about the decline of the manufacturing sector in the United States. As this graph shows, how recently this decline started depends on what you look at. If you look at the number of people employed in that sector, the decline started only a decade ago. If you look at the share of manufacturing in total employment, the steady decline has been ongoing for decades. For a nice overview of the evolution of employment in the manufacturing sector, see this article in the Journal of Economic Perspectives."