Gary F. McMahon, age 82 of Irving, TX, died at home on May 23, 2020, surrounded by his family.
Gary was born Aug. 31, 1937, in Flandreau to Eleanora Lemon and James McMahon. As a youth, Gary excelled in academics and sports, graduating from Flandreau High School in 1955. In 1958, he married the love of his life and best friend, Shirley Hahn, a childhood schoolmate.
Gary graduated from the University of South Dakota in 1959 with honors and a Bachelor of Science degree in accounting. He would later be named “Distinguished Alumnus” by the university’s business school in 1973. H professors encouraged him to pursue graduate study and in 1960, was awarded a fellowship to the University of Wisconsin, where he obtained a Masters in Business Administration in finance. While completing his education, Gary also served in the U.S. Army Reserves as an artillery captain.
Gary joined the Denver office of Haskins & Sells accounting firm in 1960. Gary went on to pass the CPA exam in 1962 and was promoted to partner in 1971. Eventually, the firm took notice of his work ethic and approachable professional style, making him managing partner of the Denver office from 1977-1983. From 1983-1989, Gary served as managing partner of the western region of the U.S. for what was now Deloitte, Haskins & Sells. While in Denver, Gary was a devoted contributor to the Boys & Girls Clubs of Metro Denver; Rotary Club of Denver, Junior Achievement and Outward Bound. Gary and Shirley were members of St. Joan of Arc Catholic Church in Arvada, the Lakewood YMCA and Denver Country Club. They owned a condo in Vail, where they spent many family vacations and were loyal fans of the Denver Broncos football team. In 1989, Deloitte Haskins & Sells and Touche Ross & Co. completed a merger and Gary was named group managing partner and Dallas office managing partner, a position requiring the family to move to Texas. Gary retired from Deloitte & Touche in 1997, having served 37 years with the company. While in Dallas, he held board positions at the Greater Dallas Chamber, Dallas Theater Center, Dallas Citizens Council, Dallas Business Committee for the Arts and the North Texas Commission. Upon retirement in 1997-98, Gary was named Chairman of the Board of the United Way of Metropolitan Dallas.
In 1999, at the age of 62 Gary was diagnosed with Parkinson’s disease. He took on “his toughest competitor” like a champ, choosing a proactive approach to coping with the disease, volunteering for studies at the National Institute of Health in Maryland and participating in local support groups. Gary continued to pursue his passions and hobbies in retirement, rarely if ever complaining about his condition. He loved exercising, cooking out and watching sports with his family, swimming with his grandchildren; golfing and reading the sports page, a tradition he continued until his last days.
He is survived by his wife of 62 years: Shirley; his daughter: Michele of Frisco (Randy); son: Michael of Dallas (Tina); and four grandchildren: Amanda, Chrissy, Ellie and Hatcher.
He is preceded in death by his parents; his brother, Thomas McMahon of Sioux Falls, and his daughter, Callae McMahon of Irving, TX.
Memorial services are pending at this time. In Gary’s honor and in lieu of flowers, the family welcomes donations to the United Way of Metropolitan Dallas via the link: www.UnitedWayDallas.org/Donate or the Parkinson’s Foundation at: www.parkinson.org
