Source: 1860 US immigration record, where he is aged 22, a labourer, listed immediately below a Peggy McVickar. BB: "William Gray arrived on May 17, 1860 aboard the Isaac Webb". He married Peggy in 1870 but by then he had already had three children to Jane Carson.
This MIGHT be him in the June 1860 census:
1860 Census:3rd Dist of 6th Ward, NYC, Wm Gray, Laborer, living in a tenement/hotel? with other men (done the 25 June 1860 for June 1, 1860 - Official Census Day)
In the 1870 census, he is living in the 17th District of the 20th ward of New York County, aged 33, born Ireland, married, a Hack Driver, with Margaret Gray, aged 34, James Gray aged 7, Mary Gray, aged 6 and Margaret, aged 4. The older Margaret is Peggy McVickar - we have the marriage record. However, he did not marry her until a few months before the census and the children seem to be from an earlier marriage to a Jane Carson.
A Samuel A Gray and an Isabella mcVicker witnessed the marriage of William and Margaret, which suggests that Samuel is indeed William's brother.
In the 2nd Enumeration of 1870, William is a Coachman. He is now 7 years older than in the first 1870 census, aged 40, living with Margaret, aged only 30 now, James aged 10, Elise aged 5, Maggie ahed 4 and Sarah, who is born now and aged 2!
(1870 Census 2nd Enumeration: This census was done as a recount for political reasons- many felt people were missed and more people = more money! Sarah Gray may actually have been missed in the first enumeration. The 2nd Enumeration is not necessarily as accurate as to ages or nationalities BUT it does, for the first time in a census, give the street addresses of the occupants. It was done in Dec-Jan 1871 timeline but was SUPPOSED to refer to June 1, 1870!! Maybe Sarah was just a baby in 2nd Enum but they decided to claim her as being born by June 1, 1870.)
In the 1880 Census, William is living in New York County, aged 44, a Driver for a Livery Stable, with his wife, "Maggie", aged 45, son James, 18, daughter Mary E, aged 16, daughter Maggie aged 14, daughter Sarah aged 9.
In the 1900 census, his wife, Margaret (McVickar) Gray, by now a widow, has a Belle Gray living with her. She is listed as a "cousin". Margaret is 62 and Belle is 32. I believe Belle is actually a cousin of Margaret's children (and therefore a niece of Margaret) and that she is Isabelle, daughter of Samuel and Sarah Gray, who also lived in New York. This is more evidence that this William is the brother of Samuel Gray. Also, his children's names do fit the family, especially his only son, James - William's father would be my great great great grandfather, James Gray. Oh, and both William and Samuel are "Hack Drivers" in New York! Plus the fact they both married McVickar girls.
Surprisingly, there is a marriage record (Charles Street United Presbyterian Church, New York) for Margaret McVickar and William Gray in the IGI, taken from Civil Records, which records her marriage in 17th Feb 1870, yes, 1870 = after William already had three children. There are three possible explanations: William married twice and the first two children were not Margaret's in the 1870 census; William and Margaret didn't marry til after they already had several children; a combination of the two where William was married before and had perhaps two children but that a third, Margaret was born to himself and Peggy McVickar before they married, which would explain why she is called Margaret.
To add to the mystery, someone clearly thinks William was married to a Jane Carson at some time:
Margaret GREY (AFN: QMDV-PH) Pedigree
Birth: 1865 New York City, Death: 1930 Yonkers, Westchester, New York, Father: William GRAY (AFN: QMDV-KS) Mother: Jane CARSON (AFN: QMDV-L0 Spouse: Walter E. HARDING (AFN: QMDV-JM).
And: James W. Gray Pedigree Birth: , , New York, Parents: Father: Wm. Gray Mother: Jane Carson, Marriages: Spouse: Cora E. Pardee, Marriage: 19 MAR 1883 Manhattan, New York, New York. (BB says this is a Civil Marriage.)
And:Husband's Name William GRAY (AFN:QMDV-KS)Born: 1833 Place: , Colerain, Northern Ireland Died: 1882 Place: New York City, , New York Wife's Name Jane CARSON (AFN:QMDV-L0) Born: 1833 Place: , Colrain, North Ireland.
This would indeed suggest that William had married twice were it not for the fact that this Margaret clearly gives her mother as Margaret McVickar when she marries Walter in 1894.