JK
John Kozlowski — 1930 US Census Record
Linked across censuses1930 United States Federal Census · Cook, Illinois
Our Model Tree links this John Kozlowski across the 1930 and 1940 US Censuses in Cook, Illinois (XGBoost, ~Confirmed) — first a son (b.~1914), then head of a 6-person household.
Age 16
b. ~1914
Male
Son
Born: Illinois
Single
1930 Census Record Details
| Census Year | 1930 |
| Location | Cook, Illinois |
| Surname | Kozlowski |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 16 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Poland |
| Mother's Birthplace | Illinois |
| Additional Details | |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Cicero Town |
| Est. Birth Year | ~1914 |
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 1930 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Helen Kozlowski | Spouse | — | 36 | ~1894 |
| John Kozlowski | Son | — | 16 | ~1914 |
| Chester Mrozek | Other | — | 18 | ~1912 |
| Lottie Kozlowski | Daughter | — | 2 | ~1928 |
| John Kozlowski | Head | — | 37 | ~1893 |
| Edward Kozlowski | Son | — | 11 | ~1919 |
Census Appearances
1930
Cook, Illinois
Son, age 16
Cook, Illinois · implied b. ~1914 — 6 household members
| Surname | Kozlowski |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 16 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Poland |
| Mother's Birthplace | Illinois |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Cook-County, Illinois
Head, age 27
Cook-County, Illinois · implied b. ~1913 — 2 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kozlow |
| Given Name | Jerome |
| Relationship to Head | Head |
| Sex | M |
| Color / Race | White |
| Age | 27 |
| Marital Status | Married |
| Birthplace | Illinois |
| 1935 Residence (City) | CHICAGO CITY |
| 1935 Residence (County) | COOK |
| Occupation | Draftsman |
| Industry | X-Ray |
| Class of Worker | PW |
| Hours Worked | 40 |
| Income (1939) | 1596 |
| Highest Grade | Hs 4 |
| 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 Kozlowski across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Kozlowski
Son · 1930 · age 16 · b. ~1914 · Illinois
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Sibling
Edward Kozlowski
Sibling · 1930 · age 11
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Lottie Kozlowski
Sibling · 1930 · age 2
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
1930 US Federal Census — Cook, Illinois
Open full size
1930 US Federal Census — Cook, Illinois
Page Contents
30 people indexed on this census page (ia:1930:illinoiscensus00reel498:0947)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 51 | Stanley Mrozek | 39 | Head | Pump Feeder | Poland |
| 52 | Joseph Dziubla | 37 | Head | Chauffeur | Illinois |
| 53 | Margaret Dziubla | 33 | Wife | Assembler | Illinois |
| 54 | Margaret Dziubla | 12 | Daughter | — | Illinois |
| 55 | Josephine Dziubla | 10 | Daughter | — | Illinois |
| 56 | George Wojtal | 39 | Head | Laborer | Poland |
| 57 | Emily Wojtal | 36 | Wife | — | Poland |
| 58 | Lottie Wojtal | 15 | Daughter | — | Illinois |
| 59 | Genevieve Wojtal | 14 | Daughter | — | Illinois |
| 60 | Edward Wojtal | 11 | Son | — | Illinois |
| 61 | Henrietta Wojtal | 5 | Daughter | — | Illinois |
| 62 | Joseph Kozlowski | 49 | Head | Carpenter | Poland |
| 63 | Stella Kozlowski | 43 | Wife | — | Illinois |
| 64 | Joseph Kozlowski | 19 | Son | Assembler | Illinois |
| 65 | Angeline Kozlowski | 18 | Daughter | Seamer | Illinois |
| 66 | Mary Kozlowski | 16 | Daughter | — | Illinois |
| 67 | John Kozlowski | 10 | Son | — | Illinois |
| 68 | Bernice Kozlowski | 7 | Daughter | — | Illinois |
| 69 | Edward Kozlowski | 1 | Son | — | Illinois |
| 70 | John Kozlowski | 37 | Head | Laborer | Poland |
| 71 | Helen Kozlowski | 36 | Wife | — | Illinois |
| 72 | John Kozlowski THIS PERSON | 16 | Son | — | Illinois |
| 73 | Edward Kozlowski | 11 | Son | — | Illinois |
| 74 | Lottie Kozlowski | 2 | Daughter | — | Illinois |
| 75 | Chester Mrozek | 18 | Nephew | Stock Clerk | Illinois |
| 76 | Thomas Kowalkowski | 30 | Head | Screw Machine Operator | Illinois |
| 77 | Stanley Kowalkowski | 28 | Brother | Chauffeur | Illinois |
| 78 | Katherine Hajek | 46 | Head | — | Czecho Slovakia |
| 79 | Mary Hajek | 21 | Daughter | Operator | Illinois |
| 80 | Joseph Hajek | 26 | Son | Sales Clerk | Illinois |
About This Record & Model Tree
This record was independently indexed by YourRoots from the 1930 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)