Baur was a native St. Louisan and one of the club's directors since 1996, and he was one of the organizers of the ownership group that has held the club since that time. In addition to his work with the Cardinals, he was also a former chairman of Southwest Bank.
"We have lost a wonderful friend, and we are deeply saddened by his sudden passing," Cardinals chairman Bill DeWitt Jr. said in a statement. "Drew loved the Cardinals and was a great partner. He will be sorely missed by all of the members of our ownership group.
"The entire Cardinals organization extends its sincere condolences to Drew's mother, Florence, his three children, Andrew, Todd and McKay, as well as his seven grandchildren and countless friends."
Baur was remembered as a gregarious, warm man who loved the Cardinals from long before he became one of the club's owners.
"He was a very outgoing and friendly personality," general manager John Mozeliak said. "He always made you feel welcome and important. And a huge Cardinal fan. ... He was always interested in the complexities of baseball, but in the end, you could tell he was a fan."
Baur had been at the Cardinals' complex in Jupiter just over a week ago, and DeWitt said he had been expected back again on Monday.
Baur and DeWitt were longtime friends, having attended high school together in the St. Louis area.
"Very outgoing," DeWitt said. "Loved life. He had a lot of fun. He always had a great attitude about things.
"You never missed him when he was around."
Prior to joining Southwest Bank, Baur served as chairman & CEO of County Bank of St. Louis, as well as president and chairman of Commerce Bank of St. Louis.
The son of the late Andrew H. Baur and the former Florence Noland, Baur attended Country Day School in St. Louis, received an A.B. degree in 1966 from Washington & Lee University in Lexington, Va., and an M.B.A. from Georgia State University in 1970.
Funeral arrangements have not been finalized at this point, nor have the club's plans for honoring Baur.
Matthew Leach is a reporter for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.