The rise of real automation making high wage high value added jobs being done by fewer and fewer people.
Low wage (relatively speaking) low value added jobs sent to third world countries.
Manufacturing jobs will be to the 21st Century what Agricultural Jobs were to the 20th. In 1900 30% of the population worked in Agriculture by 2000 less than 3% worked on farms.
One of the reasons that so much American heavy industry went out of business and overseas is precisely because of the union power and high number of manufacturing jobs. More precisely, the high number of people employed in manufacturing vs. the amount of work being done.
I hear folks often complain that they are doing the work of three people. Thirty five years ago, it was the other way around. Three people were doing the job of one.
The union rules in place in the plants my friends worked in ended up with them performing maybe two hours of actual work in a shift. For this they were paid $20+ per hour. What’s that now in inflation-adjusted wages? $50-$60 an hour? And they were shocked (shocked!) when the mills closed down.