Cornelia Wadsworth Adair, diarist and rancher, the second of the six children of Gen. James Samuel and Mary Craig (Wharton) Wadsworth, was born on April 6, 1837, in Philadelphia. She spent her early years at Hartford House, her father's country estate near Geneseo, New York. In 1855 the family left for a two-year sojourn in France and England. Soon after their return in 1857 Cornelia married Montgomery Ritchie, a grandson of Harrison Otis of Boston. Two sons were born to them. Her father and her husband died in 1864. The widowed Cornelia took her two small sons to Paris, where the older son died a few years later.
In 1867, while attending a ball in New York City given in honor of Congressman J. C. Hughes, Cornelia Ritchie met broker John G. Adair of Ireland. They were married in 1869 and afterward divided their time between America and their estates in England and Ireland. In the fall of 1874 they left Ireland to see the American West and to experience a buffalo hunt along the South Platte River in Nebraska and northeastern Colorado. Her brother had served as an aide to Philip H. Sheridan, and Cornelia Adair probably used the general's influence to obtain a military escort under Col. Richard Irving Dodge to accompany the party, which departed from Sydney Barracks in Nebraska Territory. She kept a detailed diary of the two-month journey, which included attending a council of cavalry officers and Oglala Sioux, near the South Platte. In 1918 she had it published.
In the summer of 1877, when her husband and Charles Goodnight formed a partnership to found the JA Ranch, Cornelia accompanied the party from Pueblo, Colorado, to the new ranch headquarters Goodnight had established in Armstrong County, Texas. Because the Adairs lived at the ranch only sporadically, Goodnight became its manager and, under orders from Cornelia Adair, paid high salaries for experienced, law-abiding ranchhands. After Adair died in 1885, Cornelia became Goodnight's partner. In 1887 she traded a second ranch for his one-third interest in the JA, a share that comprised 336,000 acres, 48,000 cattle, assorted mules, horses, and equipment, and rights to the JA brand. Although she was a naturalized British subject and spent most of her time in Ireland, Cornelia Adair also maintained a home in Clarendon and contributed generously to various civic projects in the vicinity of the JA Ranch, which by 1917 covered half a million acres. She provided funds to build the Adair Hospital and the first YMCA building in Clarendon and strongly supported that community's Episcopal church. She also vigorously promoted the Boy Scout movement since she knew Lord Baden-Powell and many other of its British organizers. She died on September 22, 1921, and was buried next to her husband in Ireland. In 1984 the Adairs' Glenveagh Castle, which sheltered Belgian refugees during World War I, became an Irish national park.