Fort Sumter was covered by a separate cession of land to the United States by the state of South Carolina, and covered in this resolution, passed by the South Carolina legislature in December of 1836:
“The Committee on Federal relations, to which was referred the Governor’s message, relating to the site of Fort Sumter, in the harbour of Charleston, and the report of the Committee on Federal Relations from the Senate on the same subject, beg leave to Report by Resolution:
“Resolved,
That this state do cede to the United States, all the right, title and claim of South Carolina to the site of Fort Sumter and the requisite quantity of adjacent territory, Provided, That all processes, civil and criminal issued under the authority of this State, or any officer thereof, shall and may be served and executed upon the same, and any person there being who may be implicated by law; and that the said land, site and structures enumerated, shall be forever exempt from liability to pay any tax to this state.
Who Owned Fort Sumter? | Student of the American Civil War