John (1880-1947) and Julia Theresa {Gillman} Hannigan (1881-1938) were each born in New York City in the 1880’s. They went on to have two children, each that married and had families. The list below brings the offspring of each family line.
- Dorothea Loraine Hannigan (1907-1946)
- {married John Patrick Peterson (1893-19??) in 1935}
- John Gary Peterson (1938-????)
- {married Catherine Walsh (1940-2012) in ????}
- John Gary Peterson (1938-????)
- {married John Patrick Peterson (1893-19??) in 1935}
- John Joseph Hannigan (1909-1989)
- {married Catherine Rita Donahue (1911-1983) in June 1935}
- John Dennis Hannigan (1935-????)
- {married Jo Anne Clark (1935-1963) in August 1955}
- {married Jo Hansen (1936-2008) in November 1964}
- {married Karen Sue Stanberry (1953-????) in December 1978}
- John Dennis Hannigan (1935-????)
- {married Esther Pauline Stanford (1899-1979) in 1938}
- {married Catherine Rita Donahue (1911-1983) in June 1935}