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.~1890), then head of a 6-person household.
Age 50
b. ~1890
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 | 50 |
| Marital Status | Married |
| Birthplace | Poland |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Naturalization Status | Alien |
| Additional Details | |
| Industry | 0 |
| Highest Grade | No 4 |
| 1935 Residence | Same place |
| Birth Country | Poland |
| Birthplace (normalized) | poland |
| Township / Ward | Chicago |
| Est. Birth Year | ~1890 |
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.
6 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Leo Kozlowski | Son | — | 26 | ~1914 |
| Walter Kozlowski | Son | — | 29 | ~1911 |
| Mary Kozlowski | Spouse | — | 50 | ~1890 |
| Eugene Kozlowski | Son | — | 15 | ~1925 |
| Edward Kozlowski | Son | — | 17 | ~1923 |
| Felix Kozlowski | Head | — | 62 | ~1878 |
Census Appearances
1930
Cook, Illinois
Spouse, age 40
Cook, Illinois · implied b. ~1890 — 7 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 40 |
| Marital Status | Married |
| Birthplace | Poland |
| Naturalization Status | First papers filed |
| Year of Immigration | 1910 |
| Age at First Marriage | 17 |
| Father's Birthplace | Poland |
| Mother's Birthplace | Poland |
| Can Read/Write | Yes |
| Mother Tongue | Polish |
| Birth Country | Poland |
| Birthplace (normalized) | poland |
1940
Cook-County, Illinois
Spouse, age 50
Cook-County, Illinois · implied b. ~1890 — 6 household members
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 50 |
| Marital Status | Married |
| Birthplace | Poland |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Naturalization Status | Alien |
| Industry | 0 |
| Highest Grade | No 4 |
| 1935 Residence | Same place |
| 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.
Show:
This person
Anchor record
Mary Kozlowski
Spouse · 1940 · age 50 · b. ~1890 · 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-t0627-00964-00044)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | William Kowalski | 70 | Head | Reed Assembler | Poland |
| 2 | Anna Kowalski | 58 | Wife | — | Poland |
| 3 | Victor Kowalski | 22 | Son | Assembler On Furnaces | Illinois |
| 4 | Martha Plotkowska | 60 | Head | — | Poland |
| 5 | Bernard Plotkowska | 29 | Son | Typing | Illinois |
| 6 | Eleanor Plotkowska | 21 | Daughter | Stock Girl | Illinois |
| 7 | Stanley Ciecierega | 44 | Head | Barber | Poland |
| 8 | John Batyk | 27 | Head | Shop Foreman | Illinois |
| 9 | Anastaia Pawlowska | 56 | Head | — | Illinois |
| 10 | Johanna Pawlowska | 31 | Niece | Binder | Illinois |
| 11 | Walter Goral | 25 | Head | Truck Driver | Michigan |
| 12 | Marie Goral | 20 | Wife | — | Illinois |
| 13 | Carlisle Goral | 3 | Son | — | Illinois |
| 14 | Jacqueline Goral | 1 | Daughter | — | Illinois |
| 15 | Michael Rozona | 46 | Head | Drill Press Machine Hand | Poland |
| 16 | Emily Rozona | 42 | Wife | — | Poland |
| 17 | Eleanor Rozona | 15 | Daughter | — | Illinois |
| 18 | Leonard Rozona | 2 | Son | — | Illinois |
| 19 | Anton Polivka | 49 | Head | Electric Motor Repairman | Illinois |
| 20 | Helen Polivka | 48 | Wife | — | Illinois |
| 21 | John Polivka | 30 | Son | Record Clerk | Illinois |
| 22 | Leonard Polivka | 21 | Son | Laborer Paint Pumps | Illinois |
| 23 | Anthony Polivka | 17 | Son | — | Illinois |
| 24 | Dolores Polivka | 15 | Daughter | — | Illinois |
| 25 | Bernice Kramski | 44 | Head | — | Poland |
| 26 | Joseph Kramski | 18 | Son | Bus Porter | Illinois |
| 27 | Felix Kozlowski | 62 | Head | Helper In Car Shop | Poland |
| 28 | Mary Kozlowski THIS PERSON | 50 | Wife | — | Poland |
| 29 | Walter Kozlowski | 29 | Son | Punch Press Operator | Illinois |
| 30 | Leo Kozlowski | 26 | Son | Street Car Motorman | Illinois |
| 31 | Edward Kozlowski | 17 | Son | — | Illinois |
| 32 | Eugene Kozlowski | 15 | Son | — | Illinois |
| 33 | — | None | — | — | — |
| 34 | John Trzaskos | 46 | Head | Meat Market | Poland |
| 35 | Sophie Trzaskos | 42 | Wife | — | Poland |
| 36 | Rose Trzaskos | 19 | Daughter | Beauty Operator | Illinois |
| 37 | Anthony Trzaskos | 17 | Son | — | Illinois |
| 38 | Irene Trzaskos | 15 | Daughter | — | Illinois |
| 39 | Anton Ostasiuk | 51 | Head | Molder In Brass | Poland |
| 40 | Sophie Ostasiuk | 53 | Wife | — | 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)