I think you have a point about California- Elvis spent a lot of time there during the movie years and had homes there ( I think the amount of time he spent and the association to average people was what the author of this story was alluding to in this article)
Elvis only spent limited time in his career New York,the Detroit show at the Pontiac Silverdome (in Pontiac, Michigan, a satellite city of Detroit.)although his largest crowd it is not easily associated with Elvis. But the states the author mentions are very identifiable with Elvis-
Mississippi (Tupelo hometown),
Nevada (lengthy Vegas engagements),
Hawaii (frequent vacations, 3 movies made there, Pearl Harbor Memorial benefit, Aloha worldwide special)
But I think you are correct California should have been included.