Clark worked in a chemical lab and in the forging department at the
Midvale Steel company. In 1883, he took a six-month leave of absence and traveled throughout Europe to learn from European steel companies. After his return, he led the
ordnance and railroad- and automobile-wheel production. He was promoted to second assistant superintendent and to assistant superintendent in 1886. He left Midvale Steel in 1887 and took a position as treasurer and secretary of the Flat Top Coal Land Association, which owned most of the land for mining of the
Pocahontas Coalfield. In 1900, he became a partner in E. W. Clark & Co., a bank founded by his grandfather
Enoch White Clark. He was placed in charge of public utility investments. He invested in electric light, electric power, and electric street railway companies. He served as president of the Nashville Railway and Light Company, the Northern Ohio Power Company, the
Tennessee Electric Power Company, the Portland Electric Power Company, as well as a director of several other companies. He died on June 29, 1937, at the age of 77, at his home, Cedron, in Germantown, Philadelphia. He was interred at
West Laurel Hill Cemetery in
Bala Cynwyd, Pennsylvania. ==Personal life==