[aardvarkr]

The engines are built in Hawthorne, CA before being shipped to McGregor, TX to be tested then are integrated into the final assembly in Boca Chica, TX. Every other part of the launch vehicle (besides avionics systems, also manufactured and tested in Hawthorne) is manufactured and welded on site.

[avmich]

By mass and size, Boca Chica produces the majority of the rocket. By cost and complexity - rocket engines (of Raptor kind) and control systems (of SpaceX kind - with all kinds of telemetry channels) win from Hawthorne.

[nickik]

Not the case, there are parts arriving in TX all the time. Downcomer being an example.

That said, what they are doing in Boca is clearly very impressive and its much more then just an integration facility.