- Birth Date
- 7 May 1806
- Death Date
- 24 January 1854
President of company. The Draper autobiography refers to him as "Judge" Clark.
Mary H. Clarke and Ruth H. Clarke are both listed with Isaac and his wife. It is possible that Ruth is Isaac's daughter. However, more information is needed to confirm the identities of Mary and Ruth.
- Age at Departure: 43
- Head of Household
- Bathsheba W. Smith journal, 1849 June-October, 23.
- Black, Susan Easton. Membership of the Church of Jesus Christ of Latter-day Saints: 1830-1848 (Provo, UT: Brigham Young University, [1984-1988]).
- George A. Smith's company, report, 1849 September 24.
- Historical Department journal history of the Church, 1830-2008, Supplement after 31 December 1849, 6.
- Historical Department journal history of the Church, 1830-2008, Supplement after 31 December 1849, 8B.
- Isaac Clarke Emigrating Company journal, 1849 July-October.
- William Draper autobiography, 1881, 33.
- William I. Appleby autobiography and journal, 1848-1856.