All major structures for the SLS core stage are manufactured at the NASA Michoud Assembly Facility in New Orleans.
MAF is one of the largest manufacturing plants in the world with 43 environmentally controlled acres under one roof.
Employees: >4200
1961-1972: 1st stages of the Saturn rockets
1973-2010: Space Shuttle external fuel tanks and ISS modular parts.
Current: SLS stages
Starting with Artemis III, KSC will be used for final assembly.
https://www.nasa.gov/michoud-assembly-facility/
https://en.wikipedia.org/wiki/Michoud_Assembly_Facility
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