Rome NY which I visited as part of a kayaking adventure on a local river, seem dominated by Italians (e.g. most restaurants in town were Italian). After my visit, I liked to joke that the only two things Rome, NY and Rome, Italy had in common were 1) their name, and 2) largely inhabited by Italians. Sadly Rome, NY is an ugly rust belt city.
Your perception of Rome, NY as dominated by Italians is correct. It is the top ancestry group in much of the city (and Utica). Curiously, the top ancestry group in some of the more rural parts of the county is American - something you more commonly see in the South.
Anyway, my Top Ancestry or Hispanic or Racial subgroup map based on the 2012-16 ACS is here:
https://www.thecinyc.com/top-ancestry-hisp-race
It should answer a lot of bronz4141's questions.
Those are mostly people who have no remotely recent immigrant ancestors: by and large their lineage is various people from the British Isles who emigrated to North America in the 18th century or earlier. If you wanted to coerce them into picking something, English or Scots-Irish would probably be the most accurate choices for most of them.
Ancestry.com's DNA data says they're mostly from Great Britain in some way.
