You didn't really say that they immigraated to the USA - But I assumed they did?
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I guess you have the 1900 Census:
Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM Name:Mary KennedyTitles & Terms: Residence:New York City, New York, New YorkBirth Date:May 1886Birthplace:IrelandRelationship to Head of Household:DaughterSpouse: Spouse's Titles & Terms: Spouse's Birthplace: Father:John KennedyFather's Titles & Terms: Father's Birthplace:IrelandMother:Delia KennedyMother's Titles & Terms: Mother's Birthplace:IrelandRace or Color (expanded):WhiteHead-of-household Name:John KennedyGender:FemaleMarital Status:SingleYears Married: Estimated Marriage Year: Mother How Many Children: Number Living Children: Immigration Year:1890Enumeration District:0364Page:5Sheet Letter:BFamily Number:122Reference Number:99Film Number:1241098Image Number:00293 HouseholdGenderAgeParentJohn KennedyM ParentDelia KennedyF Mary KennedyF John KennedyM Joseph KennedyM Ellen KennedyF James KennedyM
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Is this the right family? Who did Mary marry?
Just trying to help;)
Jila