The head of the banking house of Emerson McMillin, McMillin won a commission through "gallant conduct under fire" fighting for the Union Army in the Civil War, before moving to the Ohio Valley to work in the iron works and steel industries.

The Times wrote that he "made a practice of thoroughly examining the application of the scientific principles of the iron and gas industries.

"[1] Devoutly anti-slavery unlike his father, he attempted to sign up for the American Civil War at the age of seventeen.

[1] In Ohio, he became manager or president of several institutions, and afterwards focused his energies on gas properties and their consolidation and growth.

He believed in consolidating competitors as a business strategy, for example causing the merger in St. Louis of four gas companies, increasing their net profit significantly.

[4] He founded the American Light and Traction in 1900[2] for the purpose for consolidating the utility industry's small, local power suppliers,[5] and also became president.

[citation needed] McMillin provided initial funding in 1916 for the founding of Columbia Business School in New York.

[1] In late October 1924, the furnishings from the Crocker-McMillin mansion were auctioned, with profits reaching $185,000 on the third day of sales.