I have been calling for a CA split for years.
Northern and Southern would make sense, but Outer and Inner would be better politically.
At least give “inner” part of Northern CA - they need a port/access to the sea.
Outer and inner California would never be approved by the Democrats. The coastal Calif. area would be solidly Democrat, but the newly created inner state would be Republican. And a new state there would give Republicans many electoral votes in presidential elections.