igp-web.com (Ireland Genealogy Project Archives) has been one of the most active volunteer Irish genealogy websites for a long time. Each month new transcriptions and pictures of many different types of records are made available, free of change. Some records in last months upload caught my eye as they give the Irish county of origin for immigrants in various American cities.
The transcriptions come from various editions of the Freeman's Journal newspaper, from 1841 to 1845. The cities covered include New York, Boston, Detroit, Newark, and Albany, among others. The newspaper articles contain information about members of organizations and subscribers to funds for various political causes, including the Repeal Association. The Irish county of birth/origin is given for many of the members/subscribers. You can view these names at this link, in the 1840 section.
Digitized 19th century editions of the Freeman's Journal are available on the various subscription FindMyPast websites.