That’s a function of the methodology — Modesto, Fresno, and Visalia each anchor large, independent CSAs. Equally dense regions like the Midwest and Florida produced similar results, i.e. a preponderance of small city-states that practically function as a unit. I thought about manually combining them and reducing the number of city-states, but a) I wanted to minimize manual adjustments, and b) I wanted to preserve the number 100 for aesthetic reasons. Hope this sheds some light on it.