U.S. National Archives (Record Group 104, Entry 11, Branch Mint Correspondence)
National Archives entry description: Correspondence with Branch Mints and Assay Offices. 1835-1898.
National Archives catalog link is https://catalog.archives.gov/id/564471.
See also the National Archives & Records Administration numismatic finding aids at https://nnp.wustl.edu/library/archivedetail/538870, as well as entries 215 and 216 for additional New Orleans content.