In 1838, two missionary couples, the Walkers and the Eellses, joined the party going west as a reinforcement to the Oregon Mission. Just married when the trip began, Mary Walker and Myra Eells rode on horseback from Missouri to Oregon, keeping diaries throughout the months on the hazardous trail. After spending a winter at the Whitman mission in present-day Washington, the Walkers and Eellses moved north to do missionary work among the Spokane Indians.

Throughout "On to Oregon" the presence of Myra Fairbanks Eells is deeply felt, but it is Mary Richardson Walker who will be remembered for perhaps the richest diary we have from a woman pioneering in the West.