That's not really accurate. That status was developed for the transitional period after the Spanish American War, and subsequent legislation and court cases evolved that initial state.
It's really a colony, unlike US States it isn't a sovereign entity unto itself, and is essentially at the mercy of congress with respect to self-governance and other things.
It's really a colony, unlike US States it isn't a sovereign entity unto itself, and is essentially at the mercy of congress with respect to self-governance and other things.