pady51 on Family Tree Circles

I found my Great Grandfather's Death Certificate from Illinois. It states that he was born in County Down in August of 1866.
LDS files indicate that his father's name was John Ennis and his mother Jane/Jean Mc Masters.

Family tree stuck at my great grandfather, William Ennis, supposed from Northern Ireland, or Free State. Emigrated New York, 1892. Lived in Ohio and Chicago....
Any info greatly appreciated.