It's not really Puerto Rico's decision, of course; the referendum is non-binding. It's Congress's decision, in the end, though officially adding Puerto Rico as

It's not really Puerto Rico's decision, of course; the referendum is non-binding. It's Congress's decision, in the end, though officially adding Puerto Rico as a state against the wishes of a _majority_ of its citizens would be quite the odd thing to do, hence the referenda to see where things stand.