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.
The towns in the southern part of the county reached their maximum in the 19th Century. (Augusta in 1820 and Bridgewater 1830.). This would have been tied to the building of the Erie Canal which would open the area to settlement. Rome is the high point of the canal, and these southern areas are out from the Mohawk Valley so not primo farmland. Settlers would be more likely to be those who did not have much in the way of money. Settlers would be Yankees with some Dutch, German, and Ulster Scots. Elder children of large families would migrate west. When sons reached marriageable age, the father would would still be able. No bride wants to be second fiddle to her mother-in-law in the house, and the groom would be under the command of his father. The younger son would be more likely to take over the farm, perhaps caring for his widowed mother or invalid father.
After 8 to 10 generations any ties to England, Germany, etc. would be erased. I suspect that if you look at the Census records from the late 1890 or 1910 you will find most persons were New York born of New York born parents. The results will be quite different from Rome or Utica.
Areas south of Rome and Utica along the New York Thruway have increased in population post WWII. Any new factories in the area would be built here, where large single-story factories could be built. Factory buildings in Utica and Rome would either have fallen over or converted to brew pubs or restaurants. There would also be service jobs for the Thruway.
