Reports of Special Masters in all US federal courts are covered by this rule:
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Federal Rules of Civil Procedure
Rule 53 -- Masters
(e) Report.
(1) Contents and Filing. The master shall prepare a report upon the matters
submitted to the master by the order of reference and, if required to make
findings of fact and conclusions of law, the master shall set them forth in the
report. The master shall file the report with the clerk of the court and serve
on all parties notice of the filing. In an action to be tried without a jury,
unless otherwise directed by the order of reference, the master shall file with
the report a transcript of the proceedings and of the evidence and the original
exhibits. Unless otherwise directed by the order of reference, the master shall
serve a copy of the report on each party.
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So, the report becomes part of the case file. Great!

The Supreme Court has original jurisdiction in all suits between states.
Records of all original-jurisdiction cases between 1792 and 1993 are found in
Record Group 267.3.3 at the National Archives Building in Washington. The
records within the Record Group are filed by case.

The case is "State of New Jersey v. State of Delaware." The Special Master was
appointed in January 1930 (280 U.S. 529). His report had been filed by 1934.
In its decision on February 5, 1934 (291 U.S. 361), the Court said that the
report would be confirmed and the decree would be entered accordingly. The
Court approved the report and overruled all objections to it in the decree,
which came on June 3, 1935 (295 U.S. 694). The case file is probably huge, but
there's only one such report in it.

So, if anyone in or near Washington wants to volunteer, we now know where to
look.

Lowell G. McManus
Leesville, Louisiana, USA