He attended Chestnut Hill Academy and graduated in 1943 from the Avon Old Farms School in Connecticut. Mr. Stewart received a bachelor's degree in economics at Trinity College in 1950.
Mr. Stewart served in the Army Air Forces during World War II. He later attended the Wharton School of the University of Pennsylvania before taking a job with Smith, Kline & French, of which his great-grandfather, Mahlon Kline, was a founder.
In 1962, he married Joly Walton. They were longtime residents of Forge Farm in Ambler. They also kept homes in Nantucket, Mass., and Stowe, Vt.
He was a member of St. Thomas Episcopal Church of Whitemarsh.
At Smith, Kline & French, Mr. Stewart was general manager of the diagnostics division and a member of the board of directors. He retired from the division in the 1970s and from the board in 1982.
He was a founder and longtime member of the Wissahickon Valley Watershed Association. He created the Green Ribbon Trail, a 21-mile recreational area along the Wissahickon Creek.
"That was really Jim's baby," said Carol DeLancey, the association's director of events, "to preserve the land along the creek to act as a buffer to protect the creek, but also to provide some beautiful natural areas for people to enjoy."
Mr. Stewart served on the boards of the Academy of Natural Sciences, the Philadelphia Zoo, and Children's Hospital of Philadelphia.
In addition to his wife and son, Mr. Stewart is survived by daughters Lea A. Stewart, Catherine Stewart, and Elizabeth S. Hunter; sons James M. Stewart Jr. and James H. Hunter; six grandchildren; and a sister.
A memorial service will be 11 a.m. Saturday, April 27, at St. Thomas Episcopal Church of Whitemarsh, 610 Church Rd., Fort Washington.
In lieu of flowers, donations may be made to the Wissahickon Valley Watershed Association, 12 Morris Rd., Ambler, Pa. 19002-5499.
Contact Vernon Clark
at 215-854-5717 or firstname.lastname@example.org.