My name is Fred Kirkpatrick, b 1947 in Cleveland, Ohio and I run the Kirkpatrick.com website (I will be doing serious updates to that site this year. I believe we are related, connection that dates back to about 1800 in Ireland possibly in Cork Co (My great, great grandfather is Alexander Kirkpatrick, b abt 1800 in Cork Co, Ireland. He marries a Susanna Nimmo in Ireland. Think they married around 1825 and have 5-7 children, 4 girls and 3 boys. All the girls, Catherine (1827),Mary (1829), Margaret (1832), and Elizabeth (1837) were all born in Oughaval Coft Parish, CO Mayo. The boys were all born in the Province of Ulster. I believe that Susanna was also born at same parish in Mayo. Alexander may have married a 2nd time to a Jane. I believe that Andrew Kirkpatrick (father of Andrew Kirkpatrick), maybe the brother of Alexander. I read with great interest the post from "Mushroom Man" who showed Baptism of Andrew Kirkpatrick on Apr 19, 1817 and was drawn to names of two witnesses. Not sure if David Kirkpatrick is related, or to who, but found it interesting that the other witness is Susanna Kirkpatrick.
You are correct that the Kirkpatrick's first came from Scotland to Ireland around 1606-1640 in North Ireland. (The province of Ulster is today's North Ireland. The counties of most interest would be Armagh, Antrim, and Donegal). I have traced Kirkpatrick's from Ireland from about 1650 to the 1800s. I have all this information on two excel spreadsheets I can send you).
The earliest I find of any Kirkpatricks in CO Mayo is 1751 with the marriage of Mary Kirkpatrick to William Crwaford. The next time I see Mayo again is 1817. This is quite a gap from 1751 to 1817 which seems to possible indicate that the early Kirkpatricks were mostly found in the Ulster province. I would be interested in knowing more about what information you have about your family in Ireland, especially Richard since I think that Julia Kirkpatrick (b Sept 1 1835 Mayo) and Andrew (b Dec 23, 1838 Mayo) maybe related.
Fred Kirkpatrick
kirkpatrick.com
fkirkpatrick@yahoo.com