At that time, Silicon valley didn’t exist and California was barely getting mass migration. About a century later, now even the car industry seems to move toward California..

They were from a different part of the industrial era when the area was more desirable. There is a funny cycle to labor and skill labor level relative demand. Near the start skilled artisans were being disrupted and displaced by factories set up to use the unskilled masses who were previously doing things like making money off of digging through street trash for resellable goods like rags and bones. While labor conditions were often frankly horrible they often sadly were still an improvement.

Later automation reversed the trend to favor skilled labor to administer machines as being better quality and cheaper than mass cheap labor.

The point being then they had to cater to the bulk of their labor. I do not know the precise history of the region but farm families tend to produce an excess of people with larger family sizes than suburban or urban families.