John Jay (J.J.) McKelvey was born Sunday, 24 May 1863, in Sandusky, Ohio, to the parents of John McKelvey and Jane Rowland Huntington McKelvey. J.J.’s paternal grandparents were Matthew McKelvey and Nancy Adams McKelvey, and his paternal great-grandparents were William McKelvey and Mary Toppings McKelvey along with Bildad Adams and Mary Hines Adams. William McKelvey of Scotch-Irish American, Revolutionary War regality removed with an assembly after the war to the Western Reserve; where John McKelvey fashioned and financed Sandusky and a section of its first short line railroad, which eventually enveloped by the Pennsylvania Railroad. Whereas, J.J.’s maternal grandparents were Apollos Huntington and Deborah Rowland Huntington with his maternal great-grandparents being American Revolutionary War soldier Elisha Huntington and Esther Ladd Huntington and great-grandparents of the William Rowland lineage. J.J.’s five siblings included: Janet Huntington McKelvey Swift, Alice Rowland McKelvey Milne, Jennie Adams McKelvey, Charles Sumner McKelvey, and Ralph Huntington McKelvey. J.J.’s sister Alice and father John helped document their family’s English and Welsh pedigree, colonial ancestors, war-time service, and Fire Lands migration.
After successfully completing his college course, J.J. initially married Mary Clark Mattocks on 12 July 1887 in Cleveland, Cuyahoga County, Ohio, at the bride’s childhood home. Before settling into their described “Bonnie Brae” on the Hudson River at Spuyten Duyvil, J.J. and Mary visited her mother in Los Angeles, California to consolidate contiguous land for the completion of their estate on Palisade Avenue, New York City.