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.~1885), then head of a 5-person household.
Age 55
b. ~1885
Female
Spouse
Born: Germany
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 | 55 |
| Marital Status | Married |
| Birthplace | Germany |
| 1935 Residence (City) | CHICAGO CITY |
| 1935 Residence (County) | COOK |
| Naturalization Status | Naturalized |
| Additional Details | |
| Highest Grade | No 7 |
| 1935 Residence | Same place |
| Birth Country | Germany |
| Birthplace (normalized) | germany |
| Township / Ward | Chicago City |
| Est. Birth Year | ~1885 |
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.
5 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Florian Kozlowski | Son | — | 14 | ~1926 |
| Joseph Kozlowski | Head | — | 67 | ~1873 |
| Mary Kozlowski | Spouse | — | 55 | ~1885 |
| Marie Kozlowski | Daughter | — | 21 | ~1919 |
| Lucille Kozlowski | Daughter | — | 18 | ~1922 |
Census Appearances
1930
Cook, Illinois
Other, age 44
Cook, Illinois · implied b. ~1886 — 13 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kozlowski |
| Given Name | Mary S |
| Relationship to Head | Wife-H |
| Sex | F |
| Color / Race | White |
| Age | 44 |
| Marital Status | Married |
| Birthplace | Germany |
| Naturalization Status | Naturalized |
| Year of Immigration | 1902 |
| Age at First Marriage | 19 |
| Father's Birthplace | Germany |
| Mother's Birthplace | Germany |
| Can Read/Write | No |
| Mother Tongue | German |
| Birth Country | Germany |
| Birthplace (normalized) | germany |
1940
Cook-County, Illinois
Spouse, age 55
Cook-County, Illinois · implied b. ~1885 — 5 household members
| Surname | Kozlowski |
| Given Name | Mary |
| Relationship to Head | Wife |
| Sex | F |
| Color / Race | White |
| Age | 55 |
| Marital Status | Married |
| Birthplace | Germany |
| 1935 Residence (City) | CHICAGO CITY |
| 1935 Residence (County) | COOK |
| Naturalization Status | Naturalized |
| Highest Grade | No 7 |
| 1935 Residence | Same place |
| Birth Country | Germany |
| Birthplace (normalized) | germany |
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 55 · b. ~1885 · Illinois
★ You are viewing this record
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-t0627-01002-00657)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Leo Kozlowski | 42 | Son | Assembler | Illinois |
| 42 | Roman Kozlowski | 31 | Son | Shipping Clerk | Illinois |
| 43 | Wanda Kozlowski | 39 | Daughter | Office Work | Illinois |
| 44 | Joseph Kozlowski | 67 | Head | — | Russia |
| 45 | Mary Kozlowski THIS PERSON | 55 | Wife | — | Germany |
| 46 | Marie Kozlowski | 21 | Daughter | Candy Wrapper | Illinois |
| 47 | Lucille Kozlowski | 18 | Daughter | General Office | Illinois |
| 48 | Florian Kozlowski | 14 | Son | — | Illinois |
| 49 | Mary Wilczewski | 70 | Head | — | Germany |
| 50 | Leon Wilczewski | 39 | Son | Bricklayer | Illinois |
| 51 | Lillian Wilczewski | 34 | Daughter | Seamstress | Illinois |
| 52 | Mary Konczyk | 72 | Head | — | Germany |
| 53 | Walter Imbiorski | 48 | Son-in-law | Clerk | Illinois |
| 54 | May Imbiorski | 44 | Daughter | — | Illinois |
| 55 | Walter Jr Imbiorski | 14 | Grandson | — | Illinois |
| 56 | John Baumgart | 54 | Head | Bricklayer | Michigan |
| 57 | Martha Baumgart | 53 | Wife | — | Illinois |
| 58 | Esther Baumgart | 24 | Daughter | Bonner | Illinois |
| 59 | Stanley Mieznowski | 44 | Head | Baker | Poland |
| 60 | Katherine Mieznowski | 47 | Wife | — | Poland |
| 61 | Leo Mieznowski | 27 | Son | File Clerk | Illinois |
| 62 | Harry Mieznowski | 23 | Son | Accounting | Illinois |
| 63 | Wolfgang Hermann | 52 | Head | Superintendent | Germany |
| 64 | Emma Hermann | 53 | Wife | — | New York |
| 65 | Gustave Bark | 60 | Head | Insurance Broker | Germany |
| 66 | Clara Bark | 56 | Wife | — | Illinois |
| 67 | John Bates | 36 | Head | Dentist | Illinois |
| 68 | Virginia Bates | 36 | Wife | — | Illinois |
| 69 | Frank Nowakowski | 59 | Head | Tool And Die Maker | Poland |
| 70 | Alvina Nowakowski | 57 | Wife | — | Poland |
| 71 | Cecelia Nowakowski | 23 | Daughter | Stenographer | Illinois |
| 72 | Leonard Nowakowski | 20 | Son | Student | Illinois |
| 73 | Eleanor Nowakowski | 15 | Daughter | — | Illinois |
| 74 | Valentine Jacks | 31 | Head | Butcher | Illinois |
| 75 | Alvina Jacks | 29 | Wife | — | Illinois |
| 76 | Mary Jacks | 3 | Daughter | — | Illinois |
| 77 | Robert Jacks | 0 | Son | — | Illinois |
| 78 | Laura Bergman | 50 | Head | — | Illinois |
| 79 | Richard Bergman | 17 | Son | — | Illinois |
| 80 | Thomas Bergman | 14 | Son | — | 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)