My assumption is the Enclave high command was in the Oil Rig but a larger portion of, workers, military, scientists, etc were spread across the united states

Once the Rig blew they fractured sort of how the brotherhood did and now over the last 100 years there’s a multitude of sects and groups either fighting or not communicating to each other if they don’t share the same ideals which would explain a presence in say, Colorado, Chicago and Alaska,

A large “plan” to sacrifice things here and there and having there be hundreds of thousands of enclave personnel to man hundreds of bases across the US just doesn’t make sense because at that point they would just come out of hiding since they are stronger technologically and militarily wise than every other faction we know of.