Currently with the Falcon 9 they do the manufacturing in Hawthorne, initial testing in McGregor Texas, and then in Florida they have facilities for integration and inspection. They are leasing/building more facilities in Florida at Port Canaveral to handle inspection and refurbishment of landed boosters.

Eventually it might make sense to move final assembly closer to the launch site for BFR, but I would expect a lot of the component assembly (like engines) to remain in Hawthorne.