JD
John Duffy — 1940 US Census Record
Model Tree available1940 United States Federal Census · San-Francisco-County, California
Our Model Tree links this John Duffy across the 1920, 1930 and 1940 US Censuses in San-Francisco-County, California (XGBoost, ~Confirmed), with identified parents George & George — first a son (b.~1913), then head of a 5-person household.
Age 27
b. ~1913
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | San-Francisco-County, California |
| Surname | Duffy |
| Given Name | John W |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 27 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Francisco |
| 1935 Residence (County) | San Francisco |
| Additional Details | |
| Occupation | Warehouseman |
| Industry | Glass Co |
| Class of Worker | PW |
| Hours Worked | 3 |
| Income (1939) | 988 |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Occupation | Warehouseman |
| Township / Ward | San Francisco |
| Est. Birth Year | ~1913 |
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 |
|---|---|---|---|---|
| George Duffy | Head | — | 66 | ~1874 |
| Thomas Mccormick | Other | — | 17 | ~1923 |
| James Duffy | Son | — | 34 | ~1906 |
| Joseph Duffy | Son | — | 26 | ~1914 |
| John Duffy | Son | — | 27 | ~1913 |
Census Appearances
1920
San Francisco, …
Son, age 7
San Francisco, California · implied b. ~1913 — 8 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Duffy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 7 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Pennsylvania |
| Mother's Birthplace | California |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1930
San Francisco, …
Son, age 17
San Francisco, California · implied b. ~1913 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Duffy |
| Given Name | John P. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Pennsylvania |
| Mother's Birthplace | California |
| Can Read/Write | Yes |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
San-Francisco-County, California
Son, age 27
San-Francisco-County, California · implied b. ~1913 — 5 household members
| Surname | Duffy |
| Given Name | John W |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 27 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Francisco |
| 1935 Residence (County) | San Francisco |
| Occupation | Warehouseman |
| Industry | Glass Co |
| Class of Worker | PW |
| Hours Worked | 3 |
| Income (1939) | 988 |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
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 George Duffy (~0.92 confidence) and father George Duffy (~0.92 confidence) and father George Duffy (~0.92 confidence) and mother Elizabeth Duffy (~0.92 confidence). The pedigree spans 1 generation with 4 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
George Duffy
b. ~1874
Source father
● Household
· direct · ~0.92
Father
George Duffy
b. ~1874
Source father
● Household
· direct · ~0.92
Father
George Duffy
b. ~1875
Source father
● Household
· direct · ~0.92
Mother
Elizabeth Duffy
b. ~1876
Source mother
● Household
· direct · ~0.92
This person
Anchor record
John Duffy
Son · 1940 · age 27 · b. ~1913 · California
★ You are viewing this record
Sibling
James Duffy
Sibling · 1940 · age 34
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Joseph Duffy
Sibling · 1940 · age 26
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 — San-Francisco-County, California
Open full size
1940 US Federal Census — San-Francisco-County, California
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00311-00300)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Marjorie Endicott | 17 | Lodger | — | California |
| 42 | Emil G Steinberger | 35 | Head | Salesman | California |
| 43 | Helen Johnson | 55 | Mother | Beauty Operator | California |
| 44 | A. A. Quirk | 59 | Head | — | California |
| 45 | Ida B Quirk | 51 | Wife | — | Illinois |
| 46 | Permelia Buckish | 52 | Mother | — | Illinois |
| 47 | Steven R Tiffin | 34 | Head | Window Trimmer | California |
| 48 | Anita Tiffin | 32 | Wife | Bookkeeper | California |
| 49 | Jacklyn Tiffin | 13 | Daughter | — | California |
| 50 | Annie Macinnis | 64 | Mother in law | — | Canada |
| 51 | Herman H Schmidt | 65 | Head | Claim Clerk | California |
| 52 | Winifred Schmidt | 62 | Wife | — | California |
| 53 | John J Hintz | 41 | Head | Carpenter | Ohio |
| 54 | Frances Hintz | 40 | Wife | — | California |
| 55 | Richard Hintz | 11 | Son | — | California |
| 56 | Albert A Hintz | 69 | Father | — | Russia |
| 57 | Louise Hintz | 69 | Mother | — | Canada |
| 58 | James Topolos | 34 | Head | Proprietor | Greece |
| 59 | Velma Topolos | 34 | Wife | — | Washington |
| 60 | Extra Line Topolos | None | wrong | — | neighbor |
| 61 | Theo Topolos | 11 | Daughter | — | Oregon |
| 62 | Mary Ann Topolos | 9 | Daughter | — | Oregon |
| 63 | Chris Topolos | 28 | Brother | Attendant | Oregon |
| 64 | William G. Witthun | 70 | Head | Printer | New York |
| 65 | Martha Witthun | 59 | Wife | — | North Carolina |
| 66 | Gladys B Witthun | 25 | Daughter | — | California |
| 67 | Dorothy W. Witthun | 21 | Son | Exterminator | California |
| 68 | Kenneth Witthun | 16 | Son | — | California |
| 69 | Merle A. Robarts | 34 | Head | Laborer | Montana |
| 70 | Mildred Robarts | 30 | Wife | — | Minnesota |
| 71 | Carol Ann Robarts | 6 | Daughter | — | California |
| 72 | Arline Robarts | 3 | Daughter | — | California |
| 73 | Shirley Robarts | 2 | Daughter | — | California |
| 74 | Joseph Robarts | 0 | Son | — | California |
| 75 | Belle H Lowden | 79 | Head | — | New Jersey |
| 76 | George Duffy | 66 | Head | Lieutenant Of Police | Pennsylvania |
| 77 | James E. Duffy | 34 | Son | Teamster | California |
| 78 | John W Duffy THIS PERSON | 27 | Son | Warehouseman | California |
| 79 | Joseph P Duffy | 26 | Son | Bottler | California |
| 80 | Thomas G Mccormick | 17 | Nephew | — | California |
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)