Born at Durham, Greene county, New York, on the 11th of April, 1841, his parents being Almeron and Mary (Phelps) Marks, both of whom were natives of Burlington, Connecticut. Constant R. Marks spent the first ten years of his life at the place of his nativity and after his father's death lived with his grandfather in the ancestral home of the family at Burlington, Connecticut, there residing until 1859 save for the period of his absence at school. In the year mentioned his widowed mother removed with the family to Pittsfield, Massachusetts, which was the legal residence of Constant R. Marks until the spring of 1868. He was away at school, however, and during a part of the time served in the army, and he also followed the profession of teaching. Coming west in the spring of 1868, he practiced law in Chicago for a brief period and in April of that year arrived in Sioux City, Iowa, where he took up his permanent abode. He practiced independently until 1874, when he became senior member of the first of Marks & Hubbard. On the 27th of June, 1871, at Great Barrington, Massachusetts, he was united in marriage to Harriet Josephine Kilbourne. A stanch republican, he in his prime attended all political caucuses and conventions and did everything in his power to promote the success of the principles and candidates of the party but never sought public preferment for himself. In 1869, without his knowledge, he was nominated as candidate for representative in the Iowa legislature, in which he served for one term, declining another nomination. It was also without his knowledge that he was chosen a member of the Sioux City school board. Since 1869 he has been a member of Sioux City Lodge, No. 164, I.O.O.F., in which he held all the offices years ago. Mr. Marks was one of the organizers of the Sioux City Academy of Science and Letters in 1884, served as its president for many years and is now honorary president. The Sioux City Academy of Science and Letters maintains an excellent museum in the Public Library building. Mr. Marks was also identified with financial affairs for a time. He served as president of the National Bank of Sioux City. Mr. Marks also belongs to the Riverside Boat Club, of which he served as president. He attends the services of St. Thomas Episcopal church in Sioux City.