Last that I checked, San Diego is not in Texas. Californians, Arizonians, and New Mexicans are screwed. Maybe Massachusetts, New Jersey, and New York will cede some property to them. I wish the southern folks well on that endeavor. Because it is unlikely.
Have you looked at a map of South Texas recently? There's a town in Duval County called "San Diego". It's the county seat of Duval County where Lyndon Johnson won the 1948 Texas Democratic primary due to ballots cast in ballot box 13.