He is not listed with his father in 1850. He may have been on his own by age 17, or working for another family - unless they missed him in the census. He is then listed with his parents in 1860.
He was apparently married shortly thereafter, as his infant son who was born and died in 1862 is found in the local cemetery. His son's headstone lists Benjamin's wife as E. M. Wells.
Listed in 1870 as Ben, a farmer (34, KY) with his wife Elizabeth (24, OH) and children Lemuel (5), and Bell (2), both born in Illinois.
He appears to be living alone in Colorado in 1880, listed as B. Frank Wells (40, KY) widowed and working as a wood chopper.
He is next listed in the 1885 Colorado census as B.F. Wells, a day laborer (51, KY) and single, boarding with a family.
Then listed with his son Lemuel in Colorado in 1900, widowed (66, KY) working as a day laborer, having been out of work 6 months that year.