Good old History in Asphalt–a good book to have!
I went and looked in the 1880 census and there is a street labeled “Finnegansville East Riverdale Ave.”
The first person listed is John Finnigan, a 67 y.o. farmer from Ireland. The rest of Finnegansville is composed of 1 person from England, 4 New Yorkers, and 38 Irish immigrants or children of Irish immigrants. Every single person listed as living on Mosholu Ave was an Irish immigrant or the child of an Irish immigrant. Irish Town indeed!