Hi Karen,
Your links gave me some more John McCann's to look at -- hope I can figure out if any are the right one or related to my John McCann. I was looking at Irish Naming Traditions / Patterns in hopes of finding John's parents names -- if he followed traditions then his parents should be Matthew and Margaret McCann but it will not be that easy. His oldest daughter is Mary which matches his mother- in- law's name but his 2nd son's name should have been Patrick(but was Thomas) after his father-in-law. He named his 3rd son James and didn't use the name John until son #4. His 3rd daughter (Ellen) does match his wife's name. John was married to Ellen Hoy -- her parents were Patrick & Mary Hoy who arrived in New York from Ireland ~1836. I believe John had a younger sister Margaret who married Thomas Gibney -- Thomas also listed "East Meath" as his home on his naturalization papers. Sorry for the rambling but hoping someone may read this and find a link or have some ideas.
Thanks again for your help,
Patrick M. McCann