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Mary Leonard — 1940 US Census Record
Model Tree available1940 United States Federal Census · Cook-County, Illinois
Our Model Tree links this Mary Leonard across the 1920, 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed), with identified parents William & William — first a daughter (b.~1919), then head of a 5-person household.
Age 21
b. ~1919
Female
Daughter
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Cook-County, Illinois |
| Surname | Leonard |
| Given Name | Mary |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Unincorporated place Columbus Manor |
| 1935 Residence (County) | Cook |
| Additional Details | |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Unincorporated Place Columbus Manor |
| Est. Birth Year | ~1919 |
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 |
|---|---|---|---|---|
| Mary Leonard | Daughter | — | 21 | ~1919 |
| Georgia Leonard | Daughter | — | 15 | ~1925 |
| Alice Leonard | Daughter | — | 19 | ~1921 |
| Frank Leonard | Head | — | 54 | ~1886 |
| William Leonard | Son | — | 23 | ~1917 |
Census Appearances
1920
Cook, Illinois
Daughter, age 1
Cook, Illinois · implied b. ~1919 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leonard |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 1 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1930
Cook, Illinois
Daughter, age 11
Cook, Illinois · implied b. ~1919 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leonard |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 11 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Occupation | none |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Cook-County, Illinois
Daughter, age 21
Cook-County, Illinois · implied b. ~1919 — 5 household members
| Surname | Leonard |
| Given Name | Mary |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Unincorporated place Columbus Manor |
| 1935 Residence (County) | Cook |
| 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 Mary Leonard across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father William Leonard (~0.92 confidence) and father William Leonard (~0.92 confidence) and mother Lillie Leonard (~0.92 confidence) and father Frank Leonard (~0.92 confidence). The pedigree spans 1 generation with 4 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
William Leonard
b. ~1876
Source father
● Household
· direct · ~0.92
Father
William Leonard
b. ~1877
Source father
● Household
· direct · ~0.92
Mother
Lillie Leonard
b. ~1885
Source mother
● Household
· direct · ~0.92
Father
Frank Leonard
b. ~1886
Source father
● Household
· direct · ~0.92
This person
Anchor record
Mary Leonard
Daughter · 1940 · age 21 · b. ~1919 · Illinois
★ You are viewing this record
Sibling
Georgia Leonard
Sibling · 1940 · age 15
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
William Leonard
Sibling · 1940 · age 23
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Alice Leonard
Sibling · 1940 · age 19
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
40 people indexed on this census page (nara:1940:m-t0627-00790-00258)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Barbara Daniels | 2 | daughter | — | Illinois |
| 42 | Allen Cave | 34 | head | Laborer | Michigan |
| 43 | Grace D Cave | 32 | wife | — | Illinois |
| 44 | Frank Cave | 10 | son | — | Illinois |
| 45 | Tom Phillis | 45 | head | Clerk | Greece |
| 46 | Minnie Phillis | 45 | Wife | — | Illinois |
| 47 | Arthur Phillis | 9 | son | — | Illinois |
| 48 | William C Walker | 72 | head | Proof Reader | Illinois |
| 49 | Ima B Walker | 54 | wife | — | Illinois |
| 50 | Charles W Perkins | 37 | head | Candy Maker | Illinois |
| 51 | Rose D Perkins | 34 | Wife | Supervisor | Illinois |
| 52 | John Harris | 33 | head | Mechanic | Alabama |
| 53 | Doris Harris | 24 | Wife | — | Alabama |
| 54 | Charles Harris | 3 | son | — | Alabama |
| 55 | Joan Harris | 1 | daughter | — | Illinois |
| 56 | Ada Harris | 57 | mother in law | — | Alabama |
| 57 | Gustav Andresen | 36 | head | Machinist | Illinois |
| 58 | Tillie Andresen | 31 | Wife | — | Illinois |
| 59 | Hugh Cook | 30 | head | Bus Driver | Missouri |
| 60 | Helen Cook | 26 | Wife | Typist | Illinois |
| 61 | Frank Leonard | 54 | head | Foreman | Illinois |
| 62 | Alice Leonard | 19 | daughter | Clerk | Illinois |
| 63 | Mary Leonard THIS PERSON | 21 | daughter | — | Illinois |
| 64 | William Leonard | 23 | son | Clerk | Illinois |
| 65 | Georgia Leonard | 15 | daughter | — | Illinois |
| 66 | Ralph Tullo | 40 | head | Clerk | Italy |
| 67 | Maria Tullo | 42 | Wife | Clerk | Italy |
| 68 | Mike Tullo | 14 | son | — | Illinois |
| 69 | Dante Tullo | 11 | son | — | Illinois |
| 70 | William M Curtis | 39 | head | Switchman | Michigan |
| 71 | Lora Curtis | 30 | Wife | — | Oklahoma |
| 72 | Fred Marchbank | 51 | head | Clerk | Illinois |
| 73 | Elizabeth Marchbank | 81 | mother | — | Germany |
| 74 | John H Meyer | 80 | Boarder | — | Illinois |
| 75 | Edward Desmond | 60 | head | Watchman | Illinois |
| 76 | Caroline Desmond | 56 | Wife | — | Illinois |
| 77 | Lorraine Desmond | 21 | daughter | Inspector | Illinois |
| 78 | Carol Desmond | 13 | daughter | — | Illinois |
| 79 | Elizabeth Healy | 76 | head | — | Illinois |
| 80 | Leslie James Healy | 39 | son | Salesman | Illinois |
Pedigree Summary
Mary + 3 siblings
Gen 1 · 4 parents
~0.92
Max depth 4 (1900–1950 window)
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)