JC
John Costello — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Cook-County, Illinois
Our Model Tree links this John Costello across the 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed) — first a son (b.~1923), then head of a 9-person household.
Age 17
b. ~1923
Male
Son
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Cook-County, Illinois |
| Surname | Costello |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Additional Details | |
| Class of Worker | 0 |
| Highest Grade | H 1 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Chicago |
| Est. Birth Year | ~1923 |
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.
9 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Anna Costello | Daughter | — | 9 | ~1931 |
| Rose Costello | Daughter | — | 11 | ~1929 |
| John Costello | Son | — | 17 | ~1923 |
| Michael Costello | Head | — | 54 | ~1886 |
| Francis Costello | Son | — | 19 | ~1921 |
| Nora Costello | Daughter | — | 22 | ~1918 |
| Delia Costello | Spouse | — | 46 | ~1894 |
| Mary Costello | Daughter | — | 15 | ~1925 |
| Thomas Costello | Son | — | 21 | ~1919 |
Census Appearances
1930
Cook, Illinois
Son, age 5
Cook, Illinois · implied b. ~1925 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Castello |
| Given Name | John E. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 5 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Indiana |
| Can Read/Write | No |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Cook-County, Illinois
Son, age 17
Cook-County, Illinois · implied b. ~1923 — 9 household members
| Surname | Costello |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Class of Worker | 0 |
| Highest Grade | H 1 |
| 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 Costello across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Costello
Son · 1940 · age 17 · b. ~1923 · Illinois
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Sibling
Francis Costello
Sibling · 1940 · age 19
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Nora Costello
Sibling · 1940 · age 22
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Rose Costello
Sibling · 1940 · age 11
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Costello
Sibling · 1940 · age 15
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Thomas Costello
Sibling · 1940 · age 21
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Anna Costello
Sibling · 1940 · age 9
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
39 people indexed on this census page (nara:1940:m-t0627-00949-00772)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Frances Galloway | 10 | Niece | — | Illinois |
| 42 | Matthew Baldwin | 56 | Head | Postal Clerk | Illinois |
| 43 | Bessie Baldwin | 48 | Wife | — | Illinois |
| 44 | Mary Baldwin | 23 | Daughter | Stenographer | Illinois |
| 45 | Catherine Baldwin | 21 | Daughter | File Clerk | Illinois |
| 46 | Cornelius Baldwin | 17 | Son | — | Illinois |
| 47 | John Baldwin | 13 | Son | — | Illinois |
| 48 | Matthew Baldwin | 11 | Son | — | Illinois |
| 49 | Virginia Baldwin | 9 | Daughter | — | Illinois |
| 50 | Michael Baldwin | 7 | Son | — | Illinois |
| 51 | Michael Costello | 54 | Head | Policeman | Irish Free State |
| 52 | Delia Costello | 46 | Wife | — | Irish Free State |
| 53 | Nora Costello | 22 | Daughter | New Worker | Illinois |
| 54 | Thomas Costello | 21 | Son | Laborer | Illinois |
| 55 | Francis Costello | 19 | Son | New Worker | Illinois |
| 56 | John Costello THIS PERSON | 17 | Son | — | Illinois |
| 57 | Mary Costello | 15 | Daughter | — | Illinois |
| 58 | Rose Costello | 11 | Daughter | — | Illinois |
| 59 | Anna Costello | 9 | Daughter | — | Illinois |
| 60 | Emil Doerr | 46 | Head | Laborer | Ohio |
| 61 | Edith Doerr | 40 | Wife | — | Pennsylvania |
| 62 | Edison Doerr | 20 | Son | Clerk | Canada-English |
| 63 | Arthur Doerr | 18 | Son | Dryer Man | Canada-English |
| 64 | Mildred Doerr | 17 | Daughter | Typist | Canada-English |
| 65 | Evelyn Doerr | 15 | Daughter | — | Canada-English |
| 66 | Walter Doerr | 14 | Son | — | Illinois |
| 67 | Joseph Walsh | 38 | Head | Clerk | Illinois |
| 68 | Dorothy Walsh | 28 | Sister | Stenographer | Illinois |
| 69 | John Forman | 32 | Head | Trucking | New York |
| 70 | Adeline Forman | 26 | Wife | — | Illinois |
| 71 | Marie Forman | 10 | Daughter | — | Illinois |
| 72 | Jacqueline Forman | 8 | Daughter | — | Illinois |
| 73 | Marguerite Forman | 7 | Daughter | — | Illinois |
| 74 | Joseph Forman | 5 | Son | — | Illinois |
| 75 | Edward Forman | 3 | Son | — | Illinois |
| 76 | Anna Murphy | 50 | Head | — | Illinois |
| 77 | Harold Murphy | 25 | Son | Packer | Illinois |
| 78 | Archie Bollem | 26 | Son-in-law | Butcher | Illinois |
| 79 | Margaret Bollem | 26 | Daughter | Cashier | Illinois |
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)