Again you seem to either underestimate what Cali would be required to pay the US or don't want to look at the situation/process honestly. Here is just a small example of what would happen. In 2015 due to BRAC portions of Fort Gillem and Fort McPherson were merged and roughly 400 acres that was closed was sold to Tyler Perry for roughly 30 million. Now this 30 million was for a base that for the last several decades was nothing more than an administrative post; meaning there weren't major exercises like live fires, bombing practice, tank gunnery etc. Why is this important? The biggest reason is environmental clean up and insuring the land is suitable for general use; the cost for this is huge. The environmental clean up would have to occur anywhere ammo was used, fuel depots etc. I don't know what the costs were, but at the time I believe the talk was in the 10's of millions and more than the cost of the land. It was part of the reason the price was so low. While you don't have to do the environmental clean up; then you also can't use the land for anything. The idea that the US government would just strike deals with Cali for things like ports etc while possible is also unlikely for several reasons. Cali looses roughly 40 seats in the house, so they would have very little support in the house for any type of deal. There is also the emotions or anger that would steer how deals go and of course with Cali now being a foreign nation many other states would lobby for the business that previously was based in Cali. Maybe states that border Cali would strike deals to get their products from Cali, due to the cost of goods being transported being much cheaper because of proximity; however almost all other states would likely find other ways/places to get there goods. When it comes to transportation what happens to all the federal roads and rail systems; these were built with federal monies and are owned by the federal government. Maybe you think the US government will just say hey Cali keep those as a house warming gift and say good luck on your new venture; not likely IMO. So the above mentioned are just a couple of very minor things that would have to be dealt with and I promise you the federal government would require compensation for these things. The comparison of the US leaving Vietnam or Iraq is pointless because the situation is completely different. If you think that Cali leaving the US be some panacea then fine; within 2 years though those that decided to stay in Cali would feel very differently and the 6th largest economy in the world would be bleeding debt even more so than now. All the services that are provided by the federal government would need to be replaced and since Cali is such a liberal state it is likely they would put in place restrictive laws that would be a noose on any business that stayed in Cali.