I am trying to find ANYTHING regarding John Duggan born abt 1829-1834 in Ireland (What can I say but the Irish are "very casual" concerning birth dates! He had to have immigrated with my GGGrandmother Margaret O'Connor Duggan Farrell sometime after 1863 when she gave birth to her youngest Duggan child, and some time before 1869 when she married my GGGrandfather sometime before 1869/70 when my GGrandfather was born.

Could the Chicago Fire be the reason I can't find birth/death/marriage/ immigration records?

Any suggestions?