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John Mahoney — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Cook-County, Illinois
Our Model Tree links this John Mahoney across the 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed) — first a son (b.~1925), then head of a 12-person household.
Age 15
b. ~1925
Male
Son
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Cook-County, Illinois |
| Surname | Mahoney |
| Given Name | John Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 15 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Additional Details | |
| Highest Grade | No 7 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Chicago |
| Est. Birth Year | ~1925 |
Household Members
Census records only state relationship to the household head.
Pairwise kinship is derived (~90–95% accurate), not recorded.
Step/blended families and boarders can break it.
12 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Edna Mahoney | Daughter | — | 4 | ~1936 |
| Catherine Mahoney | Daughter | — | 8 | ~1932 |
| Mary Mahoney | Daughter | — | 9 | ~1931 |
| Jane Mahoney | Daughter | — | 5 | ~1935 |
| Margaret Mahoney | Daughter | — | 12 | ~1928 |
| John Mahoney | Head | — | 58 | ~1882 |
| Hewitt Mahoney | Son | — | 20 | ~1920 |
| John Mahoney | Son | — | 15 | ~1925 |
| Francis Mahoney | Son | — | 7 | ~1933 |
| Paul Mahoney | Son | — | 14 | ~1926 |
| Allen Mahoney | Son | — | 11 | ~1929 |
| Margaret Mahoney | Spouse | — | 47 | ~1893 |
Census Appearances
1930
Cook, Illinois
Son, age 5
Cook, Illinois · implied b. ~1925 — 7 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Mahoney |
| Given Name | John Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 5 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Boston |
| Mother's Birthplace | Alabama |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Cook-County, Illinois
Son, age 15
Cook-County, Illinois · implied b. ~1925 — 12 household members
| Surname | Mahoney |
| Given Name | John Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 15 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Highest Grade | No 7 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
Model Tree
An inferred pedigree reconstructed from census links — up to 4 generations within the 1900–1950 window. Closer generations are built from household co-residence; deeper ones are bridged by following a relative to their own childhood census. Confidence compounds and weakens with each generation.
Our Model Tree links John Mahoney across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Mahoney
Son · 1940 · age 15 · b. ~1925 · Illinois
★ You are viewing this record
Sibling
Margaret Mahoney
Sibling · 1940 · age 12
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Mahoney
Sibling · 1940 · age 9
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Jane Mahoney
Sibling · 1940 · age 5
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Edna Mahoney
Sibling · 1940 · age 4
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Paul Mahoney
Sibling · 1940 · age 14
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Hewitt Mahoney
Sibling · 1940 · age 20
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Catherine Mahoney
Sibling · 1940 · age 8
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Francis Mahoney
Sibling · 1940 · age 7
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Allen Mahoney
Sibling · 1940 · age 11
Source co-child of head (derived)
● Co-child · derived · ~0.88
Confirmed / household (~0.90+)
Probable / derived (~0.65–0.89)
Candidate (<0.65, unverified)
Original Census Page
1940 US Federal Census — Cook-County, Illinois
Open full size
1940 US Federal Census — Cook-County, Illinois
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00971-00393)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Marianna Senese | 16 | Daughter | — | Illinois |
| 2 | Dominic Senese | 10 | Son | — | Illinois |
| 3 | Carmen Taccini | 42 | Head | Laborer | Italy |
| 4 | Gendina Taccini | 32 | Wife | — | Italy |
| 5 | Genevieve Taccini | 11 | Daughter | — | Illinois |
| 6 | Guido Taccini | 5 | Son | — | Illinois |
| 7 | Dominic Messina | 27 | Head | Truck Driver | Illinois |
| 8 | Ann Messina | 25 | Wife | Punch Press Operator | Illinois |
| 9 | Gerard Messina | 5 | Son | — | Illinois |
| 10 | Dominic Jr. Messina | 4 | Son | — | Illinois |
| 11 | Leona Messina | 0 | Daughter | — | Illinois |
| 12 | Paul Dennehy | 36 | Head | Truck Driver | Illinois |
| 13 | Lillian Dennehy | 35 | Wife | — | Illinois |
| 14 | Arlene Dennehy | 16 | Daughter | — | Illinois |
| 15 | James Doyle | 44 | Head | Laborer | Pennsylvania |
| 16 | Pearl Doyle | 45 | Wife | — | Indiana |
| 17 | John Mahoney | 58 | Head | — | Massachusetts |
| 18 | Margaret Mahoney | 47 | Wife | — | Alabama |
| 19 | Hewitt Mahoney | 20 | Son | Junkman | Ohio |
| 20 | John Jr. Mahoney THIS PERSON | 15 | Son | — | Illinois |
| 21 | Paul Mahoney | 14 | Son | — | Illinois |
| 22 | Margaret Mahoney | 12 | Daughter | — | Illinois |
| 23 | Allen Mahoney | 11 | Son | — | Illinois |
| 24 | Mary Mahoney | 9 | Daughter | — | Illinois |
| 25 | Catherine Mahoney | 8 | Daughter | — | Illinois |
| 26 | Francis Mahoney | 7 | Son | — | Illinois |
| 27 | Jane Mahoney | 5 | Daughter | — | Illinois |
| 28 | Edna Mahoney | 4 | Daughter | — | Illinois |
| 29 | John Sime | 69 | Head | — | Illinois |
| 30 | Rose Sime | 50 | Wife | Assistant Librarian | Illinois |
| 31 | Eleanor Sime | 16 | Daughter | — | Illinois |
| 32 | Edna Lutes | 48 | Head | — | Illinois |
| 33 | Leo Innobla | 38 | Head | Burner | Oklahoma |
| 34 | Mabel Innobla | 27 | Wife | — | Illinois |
| 35 | Shirley Innobla | 2 | Daughter | — | Illinois |
| 36 | Dorothy Innobla | 1 | Daughter | — | Illinois |
| 37 | James Vaughn | 40 | Head | Clerk | Louisiana |
| 38 | Jennie Vaughn | 70 | Mother | — | Norway |
| 39 | Willis Langlin | 66 | Head | — | Illinois |
| 40 | Elizabeth Langlin | 58 | Wife | — | Ohio |
About This Record & Model Tree
This record was independently indexed by YourRoots from the 1940 United States Federal Census (NARA). Our Model Tree links this person across census decades using XGBoost-based record linkage, with per-link confidence scores. Household corroboration strengthens the signal when co-residents appear on the same census pages in multiple years.
Source: National Archives and Records Administration (NARA)