Born in Dearborn County, Indiana to farmers, Whiteaker only spent six months of formal schooling, and as a result, was almost entirely self-educated. Before moving west, he had performed odd jobs, carpentry, and volunteered for military service during the Mexican War, although his unit was never called into battle. In 1849, he joined the California Gold Rush, earning enough to move his family to a farm in Lane County, Oregon. Once in Oregon he became active in Democratic Party activities, Elected to office first as Judge of the Probate Court for Lane County (1856), then as a legislator in the Territorial Legislature (1857).