My ancestor Onias Jackson had a brother, John M. Jackson, who probably would have been in Rush County at that time, only he was only about 12 years old in 1830.It's unlikely he would have been named in that census.John was born in 1818 somewhere in Ohio, and probably came with his father (Samuel Jackson of York County, SC) and older brother Onias in the early 1820's to Rush County.They lived there for a time, then moved to Des Moines County, Iowa.Our John married Margaret Hackleman in Des Moines County, Iowa.They went to Oregon where John died soon after his arrival there in 1855.
It is believed that Onias was the son of an early wife to Onias Jackson, and that his brother John was from a second wife.
Among the early landowners in Rush County were:
Daniel Jackson Isaiah Jackson Joseph Jackson Samuel Jackson with wife Sarah Onias Jackson with wife Daraxa Laughlin (my ancestors)
When I last visited the Rush County Courthouse I did not find any John Jackson mentioned among the early landowners, but then I did not have time to examine the books too thoroughly.It's very possible I missed him.