Thank you so much for the wealth of information you have provided.
I am not definitely sure where my ancestors originated.
My Roy ancestors were from somewhere in Down as noted on
one ancestor's death record. The Roy immigrant ancestors were listed in the 1850 census as Robert Roy (age 45 in 1850) and wife, Margaret. Two children, Sarah (1840) and Robert John (1844),were born in Ireland. My great-grandmother, Elizabeth, was born at sea in 1847. I have recently found that Robert John's mother was Sarah Walker. I don't know if she died in Ireland or the US. I can't find a ship's list that matches this family so don't know if Margaret was Elizabeth's mother or a new wife married between 1847 and 1850. Robert's parents, as listed in his death record, were John and Margaret Roy. In one census record Robert was listed as being named John so he may have been John Robert and wanted to be identified that way so not to be confused with his son who was always known as Robert.
My other ancestors were John Hastings, with possibly two
wives, Jane - and Mary Ferguson. I am not sure of their origin but John and Jane may be the couple who immigrated with a man named Hope Waddell Hastings.
My third family was that of William H. Stewart and wife,
Grace. They appear to have immigrated separately with William arriving in the US first. Grace and son, John M.(born in 1846),arrived in 1850. Grace's maiden name is
listed as Branyan or Brannion in vital records. My hunch is that they may have lived in the IslandMagee area of Antrim
considering the large Brannion/Stewart population there.
All three of these families settled among the very large
Ulster Scot population in Pittsburgh/Allegheny City, Pennsylvania. Robert Roy worked in the steel mills, John Hastings was a shoemaker and William H. Stewart was listed as a wire weaver/wire worker. They all attended Presbyterian
churches but the information in those records doesn't reveal anything about their counties of origin.
The map you sent shows that the famine was substantially
milder in the areas of Down and Antrim so I wonder if there were other factors that influenced immigration.
I live in the state of West Virginia but do a lot of used book buying through Amazon so any books you might suggest would probably be available to me.
Thanks for any suggestions,