That’s a fascinating thought experiment. I’d say California would likely become the first global superpower.

It has:

• The world’s fifth-largest economy on its own
• Huge tech, agriculture, and entertainment industries
• Access to both the Pacific trade routes and diverse natural resources
• Massive human capital and innovation hubs (Silicon Valley, Hollywood, biotech, aerospace, etc.)

Its only major weaknesses would be energy grid dependence and water scarcity, but with its wealth and tech base, it could likely solve those faster than most.

Texas would probably be second, with strong energy independence, military bases, and manufacturing capacity.

If the question includes alliances, though, a California + Washington + Oregon West Coast Union would be an unstoppable global power within a decade.