JL
John Leahy — 1940 US Census Record
Linked across censuses1940 United States Federal Census · San-Francisco-County, California
Our Model Tree links this John Leahy across the 1930 and 1940 US Censuses in San-Francisco-County, California (XGBoost, ~Confirmed) — first a son (b.~1927), then head of a 5-person household.
Age 13
b. ~1927
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | San-Francisco-County, California |
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 13 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Francisco |
| 1935 Residence (County) | San Francisco |
| Additional Details | |
| Class of Worker | 0 |
| Highest Grade | 7 |
| 1935 Residence | Same House |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Township / Ward | San Francisco |
| Est. Birth Year | ~1927 |
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 |
|---|---|---|---|---|
| Margaret Leahy | Daughter | — | 25 | ~1915 |
| Timothy Leahy | Head | — | 53 | ~1887 |
| Mary Leahy | Spouse | — | 50 | ~1890 |
| Timothy Leahy | Son | — | 23 | ~1917 |
| John Leahy | Son | — | 13 | ~1927 |
Census Appearances
1930
San Francisco, …
Son, age 2
San Francisco, California · implied b. ~1928 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 2 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | California |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
San-Francisco-County, California
Son, age 13
San-Francisco-County, California · implied b. ~1927 — 5 household members
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 13 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Francisco |
| 1935 Residence (County) | San Francisco |
| Class of Worker | 0 |
| Highest Grade | 7 |
| 1935 Residence | Same House |
| 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 Leahy across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Leahy
Son · 1940 · age 13 · b. ~1927 · California
★ You are viewing this record
Sibling
Timothy Leahy
Sibling · 1940 · age 23
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Margaret Leahy
Sibling · 1940 · age 25
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-t0627-00309-00488)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Sadie Baker | 33 | Wife | — | California |
| 42 | Robert Baker | 13 | Son | — | California |
| 43 | John O'Brien | 79 | Head | — | Eire |
| 44 | William J. O'Brien | 42 | Son | Workman | California |
| 45 | Josephine A. O'Brien | 34 | Daughter | Teacher | California |
| 46 | Emil T. Heckmann | 37 | Head | Shipping Clerk | Pennsylvania |
| 47 | Mabel Heckmann | 53 | Wife | — | California |
| 48 | Timothy Leahy | 53 | Head | Conductor | Eire |
| 49 | Mary Leahy | 50 | Wife | — | Eire |
| 50 | Margaret Leahy | 25 | Daughter | Secretary | California |
| 51 | Timothy Leahy | 23 | Son | Pay Clerk | California |
| 52 | John Leahy THIS PERSON | 13 | Son | — | California |
| 53 | Donald Robt Dodds | 30 | Head | Installer | Installment | Iowa |
| 54 | Elizabeth Dodds | 31 | Wife | — | Iowa |
| 55 | Stanley Woodrow Bell | 25 | Head | Laborer | Minnesota |
| 56 | Mary Bell | 25 | Wife | — | California |
| 57 | Marilyn Bell | 0 | Daughter | — | California |
| 58 | Anna M. Bellesen | 69 | Head | — | Norway |
| 59 | Oliver B. Bellesen | 39 | Son | — | California |
| 60 | Fredrik Appelgren | 41 | Head | Ventilating Salesman | Oregon |
| 61 | Vivian Appelgren | 35 | Wife | Bookkeeper | Wisconsin |
| 62 | Maurice Oales | 38 | Head | Laundry Worker | France |
| 63 | Elise Oales | 34 | Wife | Laundry Worker | France |
| 64 | Renee Oales | 9 | Daughter | — | California |
| 65 | Maurice Roger Oales | 5 | Son | — | California |
| 66 | William C. Bollen | 36 | Head | Salesman | California |
| 67 | Marjorie Bollen | 30 | Wife | Salesman | Oregon |
| 68 | Benjamin Early | 43 | Head | Post Office Clerk | North Carolina |
| 69 | Nell E. Early | 46 | Wife | — | California |
| 70 | Thomas Murphy | 52 | Head | Policeman | Eire |
| 71 | Bridget Murphy | 50 | Wife | — | Eire |
| 72 | John Murphy | 29 | Son | School Teacher | California |
| 73 | Mary Murphy | 28 | Daughter | Stenographer | California |
| 74 | David Murphy | 27 | Son | Laborer | California |
| 75 | Thomas Murphy | 25 | Son | Laborer | California |
| 76 | Joseph J. Fitzpatrick | 63 | Head | Fireman | California |
| 77 | Mary A. Fitzpatrick | 55 | Wife | — | Northern Ireland |
| 78 | Joseph A. Fitzpatrick | 29 | Son | Clerk | California |
| 79 | Raymond T. Fitzpatrick | 9 | Son | — | California |
| 80 | Fred M. Blanck | 49 | Head | Shipping Clerk | California |
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)