https://www.numer.al/us_bls_data/figures/manufacturing-emplo...
It’s quite clear that manufacturing jobs have just been slowly and steadily disappearing over the past 70+ years.
Viewed at this scale, the debate over the bump in the last 6 years seems totally silly. Moreover it’s hard to imagine a policy that would turn that kind of trend around.
But you are right about one thing, the curve has not dipped up appreciably in the last 30 years. All I see are steps, plateau's where the level is kept before the next drop.
EDIT: can't do math or I keep thinking it's 2000's still.
A recession hits, some people get fired (sticky wages, etc, etc), the recovery comes and it's cheaper to automate stuff than hire people. Then things coast for a while. The cost of automation keeps falling, people keep getting relatively more expensive, but in good times generally you don't get people getting fired en masse because times are good and the employer is making a profit anyway. Then a recession comes, and the cycle repeats...