Chip fabrication.
Before I became a developer, I worked QA in chip fabs (both in northern and southern california) in the 90s to the 00s, the writing was on the wall, so to speak.
Do a casual google search.
https://www.marketplace.org/2021/04/21/shortage-of-semicondu...
https://en.wikipedia.org/wiki/List_of_semiconductor_fabricat...
https://www.businessinsider.com/why-us-doesnt-make-chips-sem...
https://www.bloomberg.com/graphics/2021-chip-production-why-...
et al.
Again, if you're interested in something other than what you've decided, there's Google for you. Good luck with whatever.