Yeah, fixed at ~164 thousand square miles (~400,000 km^2). Are you for real? Los Angeles and New York City proper (not the metropolitan areas) are interestingly nearly identical in official area at around 468 square miles each. But LA has a density of around 8000/mi^2 while NYC is well over 27000/mi^2. If LA merely matched NYC that'd cover another 10 million or so population by itself. The size of freaking California is not remotely a limiting factor, the limiting factor is not enough high density buildings.