I have a fairly unusual history relative to my general cohort in that between high school and college, I spent about two years working in electronics manufacturing and assembly factories (age 17 to 19) in California. I did work like injection-molding cases for devices, cutting cable and crimping connectors for computer cables, and finally, a bit of work in a laser-welding facility for precision components in Silicon Valley. The pay was remarkably good for someone my age with nothing but a high-school education, particularly when production ramped up and overtime was available (I could afford my own small apartment, and bought a car), but eventually the tedium convinced me to go to college (plus, the people upstairs in the R&D division had better pay and more interesting jobs).
Some of those jobs still exist but most of that work has been outsourced to China and Mexico and Indonesia and the Philippines. There seem to be a fair amount of high-end prototyping shops but very little mass production activity, particularly of the basic components that go into tech devices. That's because:
> ""PCB [printed circuit board] manufacturing and assembly is a very low-margin business and is largely located in Asia. It comes down to access to low-cost labor, a vast ecosystem of factory infrastructure, and flexibility. It is hard to replicate the ecosystem in the US today," said Kundojjala. "
https://www.pcmag.com/news/silicon-usa-technology-made-in-am...
The primary reason Apple and others pushed for oversea production via NAFTA trade deals, WTO membership for China, etc. is to cut labor costs. Paying kids with high-school education relatively high wages was seen as too onerous, so the factories were shipped overseas. While I worked in electronics, this exact same thing happened with the similarly-sized garment manufactuing industry.
Now if you're wondering why there's an epidemic of homelessness and poverty in California, and it's become the state with the largest income gap in the USA, well, that's why.
