Margaret has given birth to 3 children, 2 of which are still living at the time of the 1900 Census. None are enumerated in their household.

Married at time of 1880 Census; married 20 years as of 1900 Census so they must have been married just prior to the 1880 Census. BUT in the 1880 Census they have 2 children, Minnie and Elroy, ages 7 and 2. This looks like John was married previously and Minnie and Elroy were his children by another marriage.