Hi Matt,
Do you know much about John's emigration? Dates, the reason why he left, who he may have travelled with etc.? Generally more information was given at the port of arrival rather than the port of departure. If you knew which port he arrived at, this could be a good place to find more information.
Church records may be of use to you. Church of Ireland parish registers for the period up to 1870 are public records. Registers are available for about one third of the parishes, however many were destroyed in the Public Records Office in Dublin in 1922. Most are still held by the local clergy, although some are in the National Archives of Ireland and others are in the Representative Church Body Library in Dublin. A list of all surviving registers is available in the National Archives. http://ireland.anglican.org/about/42 and http://www.nationalarchives.ie/. Presbyterian registers are held in three main locations: in local custody, in the Public Records of Northern Ireland (PRONI) http://www.proni.gov.uk/ and at the Presbyterian Historical Society in Belfast. PRONI has microfilm copies of almost all registers in Northern Ireland and also lists of records held by the Presbyterian Historical Society. For the rest of Ireland, almost all records are in local custody. It can difficult to locate these as many congregations in the South have moved, amalgamated, or simply disappeared over the last sixty years. Some catholic records are held by the National Library of Ireland http://www.nli.ie/en/parish-register.aspx other records are held locally.
You might try contacting the parish administrator for Newry for more assistance.
newry@irelandxo.com
Please make sure you link anyone else in your family who is interested in their Irish heritage to our site - and indeed anyone else you know of Irish heritage.
Kind regards,
Genealogy Support
Ireland Reaching Out