A biography/family history of Mark Dearborn is included in "Montana, Its Story and Biography", Vol 2, pg 589.
Mark was born, 16 Mar 1886, to Deforest Dearborn and Emma (Davenport) Dearborn. Deforest was born in Janesville, WI, 5 Jul 1856; d. 11 Jul 1927, Childress, TX. Emma was born in New York State, and died in 1906, age 36.
Mark Dearborn was educated in Rochester, Buffalo, & Geneva, NY, and Denison, Texas. Worked in Denison & Midland, Texas, and located to Roundup, Montana, in 1909, as cashier of Roundup Coal Mining Company. In 1912, spent a short time in Spokane, WA, with the Studebaker Company & then to Denison, Texas, where was an accountant. Returned to Roundup, Montana, 1 Oct 1914. 1917, appointed City Clerk; 1918, elected Mayor of Roundup.
On 22 Sep 1908, Mark married Miss Hazel C. Sanders, b. Dennison, Texas, daughter of William P. & Corina (Wright) Sanders, natives of Wisconsin. Dearborn children: Mark Deforest IV; Ralph William; Wright Sanders.
In the 1930 Federal Census, the family was living in Spokane, WA, where Mark D. worked as a special agent, fire insurance. Hazel Dearborn d. 8 Jul 1969, Spokane, WA.