Not all death records are online. For some states one has to request and pay for a death certificate from the state vital records office. Also with the exception of New England states, most states did not keep official death records until the late 19th or early 20th C. Religious burial records are a substitute for civil death records. Obituaries or burial notices are another source of death dates.
Thank you Susannah. It's believed that he died in 1872. No one knows for sure. He was in the 1880 census, but does not show up in the 1890 census. His wife is living with her daughter, and her husband in 1890. The church records are good suggestion.