John Rooney, age 17, appears with his parents in the Raymond Township, Stearns County, Minnesota 1870 US census (June 1870), and in the Hartford Township, Todd County, Minnesota 1870 US census (August 1870) helping on the farm of his sister and her husband, John J. and Sarah B. Darcy.
John is next found in the 1880 US Census from Miles City, Custer County, Montana along with a number of other boarders. It says he's married, but no family listed with him. In the 1900 US Census, he's a boarder in Miles City, Custer County, Montana and his occupation is a day laborer. He is listed as single in 1900.
John's death certificate shows that he died Dec 6th, 1916 in Miles City, Montana, and was buried on Dec 8th, 1916 in the Catholic cemetery. His death was reported by his niece, Lillian D'Arcy. He was single.