jellybea says:

It’s not a matter of exclusion that Macy’s isn’t in places like Chico and Woodland. It’s a matter of population. Macy’s department stores tend to be rather large, with a large selection, so they need an area with a large population to support it. So there is a Macy’s in Salinas, which has about 200,000, and also serves a larger local population totaling at least 300,000. But, in the case of Woodland for example, the city only has, what, 40,000 people? Maybe 100,000 total in Yolo County?
As far as Trader Joe’s goes, they actually are building new stores all the time. But because they aren’t a huge corporate conglomerate like Safeway, they can’t afford to build a store right now in every town that could support one. They can build a few new ones at a time. Given enough time, they probably will expand to Merced, Chico, etc.
Edit: The population of the Santa Maria area is about 160,000 http://en.wikipedia.org/wiki/Santa_Maria… and a Macy’s there likely serves SLO as well. El Centro is a small town, but a Macy’s there can serve the entire Imperial Valley, which has a population of about 160,000 http://en.wikipedia.org/wiki/Imperial_Va… Again, looking back to Woodland, Yolo County only has about 160,000, but it is a VERY short drive away from Macy’s in Sacramento.