MK
Mary Kozlowski — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Cook-County, Illinois
Our Model Tree links this Mary Kozlowski across the 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed) — first a spouse (b.~1897), then head of a 10-person household.
Age 43
b. ~1897
Female
Spouse
Born: Poland
Married
1940 Census Record Details
| Census Year | 1940 |
| Location | Cook-County, Illinois |
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 43 |
| Marital Status | Married |
| Birthplace | Poland |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Naturalization Status | Naturalized |
| Additional Details | |
| Highest Grade | 8 |
| 1935 Residence | Illinois |
| Birth Country | Poland |
| Birthplace (normalized) | poland |
| Township / Ward | Chicago |
| Est. Birth Year | ~1897 |
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.
10 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Dolores Kozlowski | Daughter | — | 8 | ~1932 |
| Mary Kozlowski | Spouse | — | 43 | ~1897 |
| John Kozlowski | Head | — | 45 | ~1895 |
| Robert Kozlowski | Son | — | 5 | ~1935 |
| Stanley Kozlowski | Son | — | 17 | ~1923 |
| Chester Kozlowski | Son | — | 15 | ~1925 |
| Alice Kozlowski | Daughter | — | 12 | ~1928 |
| Richard Kozlowski | Son | — | 10 | ~1930 |
| Edward Kozlowski | Son | — | 21 | ~1919 |
| Helen Kozlowski | Daughter | — | 19 | ~1921 |
Census Appearances
1930
Cook, Illinois
Spouse, age 32
Cook, Illinois · implied b. ~1898 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 32 |
| Marital Status | Married |
| Birthplace | Poland |
| Naturalization Status | Alien |
| Year of Immigration | 1908 |
| Age at First Marriage | 21 |
| Father's Birthplace | Poland |
| Mother's Birthplace | Poland |
| Occupation | none |
| Can Read/Write | Yes |
| Mother Tongue | Polish |
| Birth Country | Poland |
| Birthplace (normalized) | poland |
1940
Cook-County, Illinois
Spouse, age 43
Cook-County, Illinois · implied b. ~1897 — 10 household members
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 43 |
| Marital Status | Married |
| Birthplace | Poland |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Naturalization Status | Naturalized |
| Highest Grade | 8 |
| 1935 Residence | Illinois |
| Birth Country | Poland |
| Birthplace (normalized) | poland |
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 Mary Kozlowski across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
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This person
Anchor record
Mary Kozlowski
Spouse · 1940 · age 43 · b. ~1897 · Illinois
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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-t0627-00969-00834)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | John Kozlowski | 45 | Head | Laborer | Poland |
| 42 | Mary Kozlowski THIS PERSON | 43 | Wife | — | Poland |
| 43 | Edward Kozlowski | 21 | Son | Clerk | Illinois |
| 44 | Helen Kozlowski | 19 | Daughter | Stenographer | Illinois |
| 45 | Stanley Kozlowski | 17 | Son | — | Illinois |
| 46 | Chester Kozlowski | 15 | Son | — | Illinois |
| 47 | Alice Kozlowski | 12 | Daughter | — | Illinois |
| 48 | Richard Kozlowski | 10 | Son | — | Illinois |
| 49 | Dolores Kozlowski | 8 | Daughter | — | Illinois |
| 50 | Robert Kozlowski | 5 | Son | — | Illinois |
| 51 | Joseph Nowak | 52 | Head | Carpenter | Poland |
| 52 | Sophie Nowak | 48 | Wife | — | Poland |
| 53 | Walter Nowak | 24 | Son | Machinist | Illinois |
| 54 | Lillian Nowak | 22 | Daughter | Typist | Illinois |
| 55 | Frank Nowak | 20 | Son | Clerk | Illinois |
| 56 | Genevieve Nowak | 18 | Daughter | Saleslady | Illinois |
| 57 | Edwin Nowak | 16 | Son | — | Illinois |
| 58 | Raymond Nowak | 14 | Son | — | Illinois |
| 59 | Adeline Nowak | 12 | Daughter | — | Illinois |
| 60 | Lorraine Nowak | 10 | Daughter | — | Illinois |
| 61 | Andrew Szymanski | 38 | Head | Truck Driver | Poland |
| 62 | Anna Szymanski | 36 | Wife | — | Illinois |
| 63 | Andrew Jr. Szymanski | 14 | Son | — | Illinois |
| 64 | Theresa Szymanski | 12 | Daughter | — | Illinois |
| 65 | Rita Szymanski | 10 | Daughter | — | Illinois |
| 66 | Donald Szymanski | 8 | Son | — | Illinois |
| 67 | Joan Szymanski | 6 | Daughter | — | Illinois |
| 68 | Thomas Zielinski | 42 | Head | Laborer | Poland |
| 69 | Stella Zielinski | 40 | Wife | — | Poland |
| 70 | Joseph Zielinski | 18 | Son | Clerk | Illinois |
| 71 | Mary Zielinski | 16 | Daughter | — | Illinois |
| 72 | John Zielinski | 14 | Son | — | Illinois |
| 73 | Frances Zielinski | 12 | Daughter | — | Illinois |
| 74 | Anthony Zielinski | 10 | Son | — | Illinois |
| 75 | Bernice Zielinski | 8 | Daughter | — | Illinois |
| 76 | Thomas Jr. Zielinski | 6 | Son | — | Illinois |
| 77 | Florence Zielinski | 4 | Daughter | — | Illinois |
| 78 | Pauline Zielinski | 2 | Daughter | — | Illinois |
| 79 | George Zielinski | 1 | Son | — | Illinois |
| 80 | Victoria Zielinski | 70 | Mother | — | Poland |
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)