Actually, automation is not new. It's called "productivity growth" and has been going on for centuries, often much faster than it is today. As we can see, manufacturing employment remained roughly even, with cyclical ups and downs, from 1970 to 2000. It then plunged as the trade deficit exploded to almost 6.0 percent of GDP in 2005 and 2006 ($1.1 trillion in today's economy).
The basic story is that manufacturing employment was declining as a share of total employment through this whole period and undoubtedly would have continued to do so regardless of what happened with trade. However, the sharp plunge in employment that we saw in the years 2000 to 2007 (pre-crash) was due to the trade deficit.
