The 1880 federal census began on June 1, 1880. This census was the first to identify each individuals relationship to the head of the household. It may provide clues to genetic diseases in earlier generations of a family. The census reported whether an individual was blind, deaf, dumb, idiotic, insane, maimed, or crippled.
The 1880 federal census includes the following information:
-head of household is listed first
-all others in the household are listed next including their relationship to the head of the household
-personal information for each person including sex, race, age, marital status, ability to read and write, birthplace, and birthplace of parents
-trade or profession and number of months unemployed
-whether an individual was blind, deaf, dumb, idiotic, insane, maimed, or crippled
Here's a link for an image of an 1880 census page: