Mack settled in
Tunbridge, Vermont, where he established a store in town and a farm where he lived in the country. He had a son,
Stephen Mack Jr., born 2 February 1798 in Tunbridge. He operated a tannery with his partner, John Mudget. Mack moved to
Detroit, Michigan, in either 1800 or 1807. He left his family behind in Vermont, where the children could be better schooled, and established a string of merchant and business ventures in Michigan. In Detroit during the
War of 1812, he was given the captaincy of a company under General
William Hull; however, the city was quickly surrendered to the British. Mack is said by his sister to have broken his sword over his knee and thrown it into the lake on hearing of the surrender. To save his property, his housekeeper housed British officers and pretended the house and business were her own. After the war, Mack rebuilt his businesses. In 1812 he became a trustee of the village of Detroit and later a director and shareholder of the
Bank of Michigan. He entered into a partnership which was known as
Mack, Conant & Sibley, which remained in business until 1821 when it was bought out by its chief competitor, the
American Fur Company. Mack became a member of the Pontiac Company and helped found Pontiac, Michigan, in 1818. He had a farm and a building firm, as well as a
sawmill and a
flour mill. He is said to have, at his own expense, paid for the extension of the turnpike Woodward Avenue to Pontiac, then a major road in Detroit. He also built a sawmill in
Rochester, Michigan, and had ventures in Ohio. In the 1820s, Mack brought his family to Michigan. They briefly lived in Detroit before settling in Pontiac around 1822. He was referred to as "Major" by a neighbor and called "Colonel" in his obituary. ==Death and legacy==