Sioux Falls, SD - Philanthropist Thomas "Denny" Sanford of Sioux Falls passed away peacefully on July 18, 2026. He was 90 years old. Denny, as he was known to many, was born Dec. 23, 1935, in St. Paul, Minn., to William and Edith (Hill) Sanford. Denny always said he wanted to live a life of significance and gave generously. His philanthropy impacted millions of lives and transformed the landscape of South Dakota and beyond.

Denny lost his mother to breast cancer when he was four and he began working at his father's garment shop at the age of eight. These early years instilled in him a desire to help others, a commitment that lasted throughout his life. After graduating from the University of Minnesota in 1958 with a degree in psychology, Denny began a successful career in sales, marketing and materials distribution. His experiences led him to establish Contech, Inc., a Minneapolis-based company that manufactured sealants, coatings and adhesives.

After selling the company, Denny purchased a bank in Sioux Falls, South Dakota, in 1986. He renamed it First PREMIER Bank and expanded into the credit card sector with PREMIER Bankcard. Today, PREMIER is considered one of the nation's strongest financial organizations, which allowed Denny to focus on philanthropic endeavors in his later years.

He was a champion for charitable organizations that benefit children, health care, higher education, workforce development and the arts. His first significant donation was a $2 million gift in 1999 to Children's Home Society of South Dakota. In 2007, he made history with his $400 million gift to the Sioux Valley Health System, which became Sanford Health. Additional gifts to Sanford Health were used to establish specialty facilities, including the Edith Sanford Breast Center, Sanford Children's Hospital, Sanford Imagenetics and Sanford Health's Virtual Care Initiative. Passionate about the power of education, Denny funded numerous scholarships including South Dakota's Build Dakota and Freedom scholarship programs. He was also instrumental in construction of the Denny Sanford PREMIER Center in Sioux Falls and provided significant gifts to the Sanford Underground Research Facility (SURF) and Crazy Horse Memorial in the Black Hills of South Dakota.

Over the course of his life, Denny provided more than $4 billion in gifts to charitable organizations. While he focused largely upon South Dakota initiatives, he also funded projects in communities where he felt a strong connection. He was instrumental in establishing the Sanford Consortium for Regenerative Medicine in San Diego and the Sanford-Burnham-Prebys Medical Discovery Institute in La Jolla, California, the University of California-San Diego, and Rady Children's Hospital. Denny's passion for social and emotional research and education led to the development of the Sanford Harmony and Inspire Programs at Arizona State University, and the Sanford College of Education at National University in San Diego.

The magnitude of Denny's overall charitable contributions has been recognized in various news sources, including the Chronicle of Philanthropy which named him one of the 50 most generous philanthropists. He has also been the recipient of many prestigious awards, among them the Horatio Alger Association Distinguished American Award.

Denny was known for his humility and compassion for others. He chose to live a life of significance by inspiring others to join in his philanthropic giving. He lived by the motto: "Aspire to inspire before you expire."

Denny was also devoted to his family and friends, with whom he pursued his other pastimes, including golf and sailing. Left to cherish his memory are his brother Charles "Chuck" (Nancy) Sanford and sons Scott (Rada) and Bill (Andrea) and three grandchildren.

Arrangements for a family service followed by a community celebration are pending. In lieu of flowers, plants or memorial gifts, please honor Denny by giving to the charity of your choice.

Cards to the family may be sent to:

PO Box 2110

Sioux Falls, SD 57101-2110