He was one of the "forty-niners" who crossed the plains to California. He made a second trip there about 1851 (Severance, B. Frank. Genealogy and biography of the descendants of Walter Stewart of Scotland and of John Stewart who came to America in 1718 and settled in Londonderry, N.H. Greenfield, Mass. : T. Morey & Son, 1905, pg. 123).
Grave marker has death date as 1866, but Severance and findagrave agree on 11/23/1865.