If every state of the USA declared war against each other, which would win?
quora.comTexas is the biggest state with vast resources and self sufficient in food and oil. After securing their backs with Arizona, they need to mount a decisive offensive to annex the other southern states and create a buffer zone against any threat from the north.
Don't forget that with Texas occupied fighting other states, their resources to guard the border with Mexico would be stretched pretty thin. I'm sure the cartels would seize the opportunity to move north. You'd want to protect the border at the same time you're fighting a war, and that would be tough. The same would apply to California to a lesser extent because of a smaller border.
While I understand it's meant to be a silly question, a serious treatment would need to remember that many of the states have nuclear weapons.
Many countries also have nuclear weapons, but they have not been used in combat since WWII. The big deterrents would be that any detonation within the continental US would likely have a detrimental impact on the state who launched it, and that any retaliation would result in mutual destruction.
The premise is that the 50 states are at war with each other. It's hard to imagine the reasons for such a situation in the first place. If NM were losing to Texas on the south and Colorado on the north and the population being massacred then perhaps the modern day Curtis Le May - or Jack D. Ripper - would say it's a justified nuclear war since they are being destroyed anyway.
That lack of a real justification for the war in the first place is what makes it hard to have any meaningful response to the topic.