See: Tips for Determining Port of Arrival
Family Search (LDS), Ancestry, Find My Past, and Fold3 have Immigration, Travel, and Naturalization records.
Some US newspapers published "information wanted" ads of people searching for their missing Irish relatives.
Ads from The Boston Pilot were once online at Boston College. Ancestry and Find My Past now have a searchable database of those ads, but you can also download the dataset from Harvard dataverse.
The Irish American was based in New York City. Ads starting from 1857 were once online but are now in the Internet archives.
The Truth Teller was based in New York City. Ads from 1825 to 1844 were published in the book Voices of the Irish Immigrant by Diane Fitzpatrick Haberstroh and Laura Murphy DeGrazia.
Irish Friends and Relatives from the "Information Wanted" Ads in The Irish American, 1850-1871 was by the same authors.
Look for these book resources here and here at your nearest genealogy library.
Sometimes people who emigrated wrote back home and stayed in touch with the locals. Their stories may have ended up in an Irish newspaper. Sometimes the descendants of emigrants wrote back home to Irish newspapers with genealogy inquiries that got published.
New Brunswick: Teetotal
Ontario: Corktown
Ontario: Peter Robinson settlers of Ottawa. North Cork settlers.
Maine: Androscoggin County had a heavy influx of Cork Irish, often coming in from Boston. According to a local Androscoggin expert, the Irish population of Portland (Cumberland County) were more Galway-based.
Massachusetts: Scituate is considered the most Irish town in the United States and considers West Cork a "sibling."
Michigan: Corktown was the name of a historic district of Detroit, Michigan.
Montana: Butte. Many southwest Cork Irish came here.
Wyoming: Casper. Many southwest Cork Irish came here.