John - I see it is over a year since you posted your message and no-one has replied!I hope you're still there!
Tierney is an old Irish name, and I believe they were very prominent in medieval times in Co Mayo.My maiden name was Maguire, and my family were also prominent at that time - in Co Fermanagh.My greatgrandfather, John Maguire, married Anne Tierney in Enniskillen, Co Fermanagh in the 1800s.Her nephew, Hugh Tierney lived in the same town in Wales as my father.
I am trying to find out if all the Tierneys are related to each other, as the Maguires are.I have found out that Blessed Edmund Rice who founded the Christian Brothers, was the son of Margaret Tierney (married to his father of course!).
I am living in England, and it is often more difficult for us to find connections because when the Irish famine happened and millions of people left Ireland, it was then all part of the UK and therefore they were not immigrants and there weren't any records kept of passengers on boats here.However, you in the US have all those records, so it's a lot easier for you!
Good luck in your family history search.We may be cousins hundreds of times removed!