Basically, because of a huge apple crop failure in the Santa Clara Valley, as well as having recently laid railroad crossing the area (this was in the 1800’s), apple growers in the Pajaro Valley (between Santa Clara and Salinas) began shipping their apples to markets farther away than usual. This eventually boomed into a global scale thing, with Pajaro Valley apples being sold in New York, then London, and even places like South Africa.

After developing a successful global distribution model, growers in Washington state took notice. Apples were shipped on northern rail lines after the growing season in Fall. No ice needed.

Soon, other industries followed (Salinas Valley lettuce included). This blossomed into the global food system we know today.

Tl;dr: Money in proto-silicon valley was used to start up the global food system