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Mary Monahan — 1940 US Census Record
Model Tree available1940 United States Federal Census · Douglas-County, Illinois
Our Model Tree links this Mary Monahan across the 1920, 1930 and 1940 US Censuses in Douglas-County, Illinois (XGBoost, ~Confirmed), with identified parents Thomas & Lillian — first a daughter (b.~1906), then head of a 3-person household.
Age 34
b. ~1906
Female
Daughter
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Douglas-County, Illinois |
| Surname | Monahan |
| Given Name | Mary C. |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 34 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Arcola City |
| 1935 Residence (County) | Douglas |
| Additional Details | |
| Occupation | Secretary |
| Industry | Broom Corn Office |
| Class of Worker | PW |
| Hours Worked | 35 |
| Income (1939) | 600 |
| Highest Grade | C 4 |
| 1935 Residence | Same House |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Occupation | Secretary |
| Township / Ward | Arcola City |
| Est. Birth Year | ~1906 |
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.
3 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Lillian Monahan | Spouse | — | 63 | ~1877 |
| Mary Monahan | Daughter | — | 34 | ~1906 |
| Thomas Monahan | Head | — | 70 | ~1870 |
Census Appearances
1920
Douglas, Illinois
Daughter, age 14
Douglas, Illinois · implied b. ~1906 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Monahan |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 14 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | New York |
| Can Read | Yes |
| Can Write | Yes |
| Speaks English | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1930
Douglas, Illinois
Daughter, age 24
Douglas, Illinois · implied b. ~1906 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Monahan |
| Given Name | Mary C |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 24 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | New York |
| Occupation | journalist |
| Industry | newspaper |
| Class of Worker | W |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Douglas-County, Illinois
Daughter, age 34
Douglas-County, Illinois · implied b. ~1906 — 3 household members
| Surname | Monahan |
| Given Name | Mary C. |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 34 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Arcola City |
| 1935 Residence (County) | Douglas |
| Occupation | Secretary |
| Industry | Broom Corn Office |
| Class of Worker | PW |
| Hours Worked | 35 |
| Income (1939) | 600 |
| Highest Grade | C 4 |
| 1935 Residence | Same House |
| 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 Monahan across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father Thomas Monahan (~0.92 confidence) and mother Lillian Monahan (~0.92 confidence) and mother Lillian Monahan (~0.92 confidence). The pedigree spans 1 generation with 3 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
Thomas Monahan
b. ~1870
Source father
● Household
· direct · ~0.92
Mother
Lillian Monahan
b. ~1877
Source mother
● Household
· direct · ~0.92
Mother
Lillian Monahan
b. ~1877
Source mother
● Household
· direct · ~0.92
This person
Anchor record
Mary Monahan
Daughter · 1940 · age 34 · b. ~1906 · 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 — Douglas-County, Illinois
Open full size
1940 US Federal Census — Douglas-County, Illinois
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00795-00033)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Nettalee Jarvis | 41 | Boarder | Agent | Indiana |
| 42 | Thomas O'Neil | 48 | Head | Laborer | Illinois |
| 43 | Martha O'Neil | 42 | Wife | — | Illinois |
| 44 | Thomas Jr. O'Neil | 16 | Son | — | Illinois |
| 45 | Martha Ann O'Neil | 9 | Daughter | — | Illinois |
| 46 | Jerry O'Neil | 6 | Son | — | Illinois |
| 47 | Gene O'Neil | 2 | Son | — | Illinois |
| 48 | John Mccord | 70 | Head | Doctor | Kentucky |
| 49 | Blanche Mccord | 62 | Wife | — | Kentucky |
| 50 | Lillie Logan | 60 | Head | — | Illinois |
| 51 | Ralph Logan | 36 | Son | Proprietor | Illinois |
| 52 | Edward Hammett | 82 | Head | Retired | England |
| 53 | Ozzie Harris | 70 | Head | Janitor | Illinois |
| 54 | Attie Harris | 63 | Wife | — | Illinois |
| 55 | Pauline Harris | 41 | Daughter | Bookkeeper | Illinois |
| 56 | Fern Covalt | 29 | Roomer | Teacher | Illinois |
| 57 | Earl Corninean | 33 | Roomer | Commerce | Michigan |
| 58 | George Sitz | 32 | Head | Clerk | Illinois |
| 59 | Blanche Sitz | 28 | Wife | — | Illinois |
| 60 | Josephine Osborne | 25 | Head | Housekeeper | Illinois |
| 61 | Jeanine Osborne | 8 | Daughter | — | Illinois |
| 62 | Dora Walker | 59 | Mother | — | Illinois |
| 63 | Stephen Walker | 74 | Head | — | Illinois |
| 64 | Sam Slutzky | 59 | Head | Buyer | Poland |
| 65 | Minnie Slutzky | 41 | Wife | — | Illinois |
| 66 | Herman Slutzky | 16 | Son | — | Illinois |
| 67 | Thomas Monahan | 70 | Head | Buyer | Illinois |
| 68 | Lillian Monahan | 63 | Wife | — | New York |
| 69 | Mary C. Monahan THIS PERSON | 34 | Daughter | Secretary | Illinois |
| 70 | Frederick Shrader | 27 | Head | Embalming | Illinois |
| 71 | Helen Shrader | 21 | Wife | — | Illinois |
| 72 | Clara Shrader | 62 | Mother | — | Illinois |
| 73 | Bertha Gaylord | 66 | Head | — | Ohio |
| 74 | Emma Albin | 60 | Head | — | Illinois |
| 75 | Bertrand Gordon | 58 | Head | Commissioner | Ohio |
| 76 | Bertrand Jr. Gordon | 30 | Son | Proprietor | Illinois |
| 77 | Duane Gordon | 23 | Son | Ditching | Illinois |
| 78 | Richard Gordon | 20 | Son | Laborer | Illinois |
| 79 | Glenn Gordon | 16 | Son | — | Illinois |
| 80 | Dorothy Gordon | 15 | Daughter | — | Illinois |
Pedigree Summary
Mary
Gen 1 · 3 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)