Cattle rancher; President, Arizona Cattle Growers' Association, 1932, Member, Arizona Livestock Sanitary Board, 1931-1932, worked with various credit banks and the Hearst Corporation analyzing livestock and ranching operations. Managed primary campaign for Sidney P. Osborn, Democratic nominee for Governor of Arizona, 1940. McKinney was a 1942 candidate for the Democratic nomination for Governor of Arizona.
Correspondence, financial papers, reports, and related materials dealing with activities in the Arizona Cattle Growers' Association, the Arizona Livestock Sanitary Board, various farm credit associations, the livestock interests of the Hearst Enterprises, and the California Cattlemen's Association. Included is political material concerning Osborn's 1940 campaign, and McKinney's own campaign in 1942.