His eldest son, William Hamilton Mitchell [wd], succeeded him at the helm of the Continental Illinois National Bank and later became the director of Texaco, one of the largest and most successful oil companies of the era.

[2] In 1918, William married Chicago socialite Ginevra King—the first love of writer F. Scott Fitzgerald—and inspired the character of Tom Buchanan in The Great Gatsby.

"Jack" Mitchell, married J. Ogden Armour's daughter Lolita in 1920 at the family's estate in the upper-class enclave of Lake Forest, Illinois.

[7] His half-sister Hortense Lenore Mitchell (1871–1962) married the British architect, art dealer and collector Arthur Acton (1873–1953).

[8][9] John J. Mitchell died in Libertyville, Illinois on October 29, 1927, from injuries suffered in a car accident which also claimed the life of his wife.