Homer initially traveled to the Salt Lake Valley in the Willard Richards Company in 1848 as a captain of ten. He traveled with his wife, Asenath Melvina Robinson Banker, and their three children Julia Emily, John Chapman, and William Platt Putnam, and his brother Chapman Duncan and his wife Martha Jones.
At the end of a mission, he traveled home as captain of the Homer Duncan Company in 1857.
At the end of another mission, he traveled home again as captain of the Homer Duncan Company in 1861.
At The end of a third mission, he traveled home, again as captain, of the Homer Duncan Company in 1862.
All of these were indicated in his autobiographical sketch of 1900.
According to his obituary, he served missions to Canada (1839), the Eastern States, England, and Texas. It also states that he "crossed the plains 21 times before the advent of the railroad and has never made that journey by steam power."