JD
John Duffy — 1940 US Census Record
Model Tree available1940 United States Federal Census · Cook-County, Illinois
Our Model Tree links this John Duffy across the 1920, 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed), with identified parents Thomas & John — first a son (b.~1914), then head of a 5-person household.
Age 26
b. ~1914
Male
Son
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Cook-County, Illinois |
| Surname | Duffy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 26 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Additional Details | |
| Occupation | Clerk |
| Industry | Post Office |
| Class of Worker | GW |
| Hours Worked | 40 |
| Income (1939) | 2100 |
| Highest Grade | H-4 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Occupation | Clerk |
| Township / Ward | Chicago |
| 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.
5 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Mary Duffy | Daughter | — | 19 | ~1921 |
| John Duffy | Head | — | 58 | ~1882 |
| John Duffy | Son | — | 26 | ~1914 |
| James Duffy | Son | — | 24 | ~1916 |
| Anna Duffy | Spouse | — | 52 | ~1888 |
Census Appearances
1920
Cook, Illinois
Son, age 7
Cook, Illinois · implied b. ~1913 — 9 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Duffy |
| Given Name | John J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 7 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Can Read | Yes |
| Can Write | Yes |
| Speaks English | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1930
Cook, Illinois
Son, age 17
Cook, Illinois · implied b. ~1913 — 9 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Duffy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Cook-County, Illinois
Son, age 26
Cook-County, Illinois · implied b. ~1914 — 5 household members
| Surname | Duffy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 26 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Chicago |
| 1935 Residence (County) | Cook |
| Occupation | Clerk |
| Industry | Post Office |
| Class of Worker | GW |
| Hours Worked | 40 |
| Income (1939) | 2100 |
| Highest Grade | H-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 Duffy across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father Thomas Duffy (~0.92 confidence) and father John Duffy (~0.92 confidence) and mother Mary Duffy (~0.92 confidence) and mother Anna Duffy (~0.92 confidence). The pedigree spans 1 generation with 4 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
Thomas Duffy
b. ~1877
Source father
● Household
· direct · ~0.92
Father
John Duffy
b. ~1882
Source father
● Household
· direct · ~0.92
Mother
Mary Duffy
b. ~1884
Source mother
● Household
· direct · ~0.92
Mother
Anna Duffy
b. ~1888
Source mother
● Household
· direct · ~0.92
This person
Anchor record
John Duffy
Son · 1940 · age 26 · b. ~1914 · Illinois
★ You are viewing this record
Sibling
James Duffy
Sibling · 1940 · age 24
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Duffy
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-t0627-00982-00787)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Catherine Benson | 23 | Daughter | Stenographer | Illinois |
| 42 | Paul Benson | 22 | Son | — | Illinois |
| 43 | Martin Benson | 20 | Son | Laborer | Illinois |
| 44 | Thomas Benson | 16 | Son | — | Illinois |
| 45 | John Benson | 10 | Son | — | Illinois |
| 46 | William Wood | 52 | Head | Coal Handler | England |
| 47 | Anne Wood | 47 | Wife | — | Illinois |
| 48 | Lydia Granger | 84 | Head | — | Maine |
| 49 | Margaret Granger | 59 | Daughter | Stenographer | Illinois |
| 50 | Lora Granger | 50 | Daughter | Bookkeeper | Illinois |
| 51 | Daisy Richardson | 68 | Sister | — | Illinois |
| 52 | George Casey | 75 | Head | — | Ireland |
| 53 | Mary Casey | 56 | Wife | — | Illinois |
| 54 | Mary H. Casey | 37 | Daughter | Stenographer | Illinois |
| 55 | Eileen Casey | 33 | Daughter | Stenographer | Illinois |
| 56 | Frank Ostegel | 64 | Head | — | Illinois |
| 57 | Hazel Ostegel | 32 | Wife | — | Oklahoma |
| 58 | John Rooney | 48 | Head | Bridge Tender | Irish Free State |
| 59 | Mary Rooney | 40 | Wife | — | Irish Free State |
| 60 | Mary Rooney | 18 | Daughter | New Worker | Illinois |
| 61 | John Rooney | 16 | Son | — | Illinois |
| 62 | Dorothy Rooney | 15 | Daughter | — | Illinois |
| 63 | Anna Rooney | 12 | Daughter | — | Illinois |
| 64 | William Rooney | 10 | Son | — | Illinois |
| 65 | John Duffy | 58 | Head | Stationary Engineer | Irish Free State |
| 66 | Anna Duffy | 52 | Wife | — | Irish Free State |
| 67 | John Duffy THIS PERSON | 26 | Son | Clerk | Illinois |
| 68 | James Duffy | 24 | Son | Shipping Clerk | Illinois |
| 69 | Mary Duffy | 19 | Daughter | Telephone Operator | Illinois |
| 70 | Patrick Doty | 70 | Head | — | Irish Free State |
| 71 | Mary Doty | 60 | Wife | — | Irish Free State |
| 72 | Thomas Doty | 34 | Son | Laborer | Irish Free State |
| 73 | Michael Doty | 33 | Son | Motorman | Irish Free State |
| 74 | Gerald Doty | 20 | Son | Cashier | Irish Free State |
| 75 | Louis Daucher | 51 | Head | Truck Helper | Missouri |
| 76 | Louise Daucher | 48 | Wife | — | Poland |
| 77 | Hugh Mcdonald | 40 | Head | Truck Driver | Illinois |
| 78 | Genevieve Mcdonald | 39 | Wife | Switchboard Oper. | Illinois |
| 79 | Edward Keegan | 36 | Lodger | Truck Driver | Illinois |
| 80 | Sarah Keegan | 33 | Lodger | — | Illinois |
Pedigree Summary
John + 2 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)