Do you know when the 1880 census year begins and ends? Who is included in that census? Not sure? You will find the answers at the top of the 1880 census form. What you find there may give you clues for further research.
Here is what is written on the 1880 census:
Note A. - The Census Year begins June 1, 1879, and ends May 31, 1880.
Note B. - All persons will be included in the Enumeration who were living on the 1st day of June, 1880. Children BORN since June 1, 1880, will be OMITTED. Members of Families who have DIED Since June 1, 1880, will be INCLUDED. 
Note C. - Questions No. 13, 14, 22 and 23 are not to be asked in respect to persons under 10 years of age. 
Reading the instructions or hints is always a good thing.
 The same dates apply to the Non-Population Schedules (Agriculture, Manufacturing, Mortality and Social Statistic Schedules).
 Capitalization of words appears on the census form.
 Question No. 13 asks the person's occupation. Question No. 14 asks the number of months employed. Question No. 22 asks if the person cannot read. Question No. 23 asks if the person cannot write.
Published 21 April 2017, Western Kentucky Genealogy Blog, http://wkygenealogy.blogspot.com/