Some of the best information uncovered, comes from the numerous official US Government docuмents between the US Italian Embassy in Rome and Washington[/b] in the 20th century. The US did not have formal diplomatic ties with Vatican City, so both sides often communicated through the US Italian Embassy in Rome, as their sole point of contact.
To research exclusively at the various archival libraries, only in DC, for "Vatican City to US" docuмents, provides little relevant data.