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Mary Larsen — 1940 US Census Record
Linked across censuses1940 United States Federal Census · San-Mateo-County, California
Our Model Tree links this Mary Larsen across the 1930 and 1940 US Censuses in San-Mateo-County, California (XGBoost, ~Confirmed) — first a daughter (b.~1919), then head of a 8-person household.
Age 21
b. ~1919
Female
Daughter
Born: Pennsylvania
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | San-Mateo-County, California |
| Surname | Larsen |
| Given Name | Mary C. |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | San Mateo City |
| 1935 Residence (County) | San Mateo |
| Additional Details | |
| Highest Grade | Hs 3 |
| 1935 Residence | Same place |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
| Township / Ward | San Mateo City |
| 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.
8 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Alfred Larsen | Son | — | 16 | ~1924 |
| Andrew Larsen | Son | — | 12 | ~1928 |
| John Larsen | Son | — | 22 | ~1918 |
| Mary Larsen | Head | — | 44 | ~1896 |
| Frank Larsen | Son | — | 19 | ~1921 |
| Mary Larsen | Daughter | — | 21 | ~1919 |
| Lawrence Larsen | Son | — | 10 | ~1930 |
| Louis Larsen | Son | — | 20 | ~1920 |
Census Appearances
1930
San Mateo, …
Other, age 11
San Mateo, California · implied b. ~1919 — 9 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Larsen |
| Given Name | Mary |
| Relationship to Head | Dau |
| Sex | F |
| Color / Race | White |
| Age | 11 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| Father's Birthplace | Denmark |
| Mother's Birthplace | Ireland FS |
| Occupation | none |
| Can Read/Write | Yes |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
1940
San-Mateo-County, California
Daughter, age 21
San-Mateo-County, California · implied b. ~1919 — 8 household members
| Surname | Larsen |
| Given Name | Mary C. |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | San Mateo City |
| 1935 Residence (County) | San Mateo |
| Highest Grade | Hs 3 |
| 1935 Residence | Same place |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
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 Larsen across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
Mary Larsen
Daughter · 1940 · age 21 · b. ~1919 · California
★ You are viewing this record
Sibling
Louis Larsen
Sibling · 1940 · age 20
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Alfred Larsen
Sibling · 1940 · age 16
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Andrew Larsen
Sibling · 1940 · age 12
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Frank Larsen
Sibling · 1940 · age 19
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Lawrence Larsen
Sibling · 1940 · age 10
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
John Larsen
Sibling · 1940 · age 22
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-Mateo-County, California
Open full size
1940 US Federal Census — San-Mateo-County, California
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00330-00372)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Donna Joan Mcmasters | 5 | daughter | — | California |
| 2 | Ernest O. Klapp | 53 | head | Bookkeeper | Pennsylvania |
| 3 | Anna M. Klapp | 52 | wife | — | Pennsylvania |
| 4 | Noomer Klapp | 23 | son | Blank | California |
| 5 | James B. Reynard | 71 | head | Plumber | Scotland |
| 6 | May Reynard | 71 | wife | — | Scotland |
| 7 | Jean Mcdonald | 61 | sister-in-law | Clerk | Scotland |
| 8 | Charles S. Blake | 65 | head | — | California |
| 9 | Elvira Blake | 61 | wife | — | California |
| 10 | Bryan Mcmaine | 24 | head | Vulcanizing | Kansas |
| 11 | Frances Mcmaine | 25 | wife | — | Colorado |
| 12 | James Roper | 35 | head | Attendant | Missouri |
| 13 | Lillian D. Roper | 28 | wife | — | California |
| 14 | Fred Bank | 51 | head | Glazier | California |
| 15 | Louise Bank | 49 | wife | — | California |
| 16 | Fred Jr. Bank | 26 | son | Glazier | California |
| 17 | Dorothy Bank | 23 | daughter | Bookkeeper | California |
| 18 | Majorie Bank | 17 | daughter | — | California |
| 19 | Joseph Bank | 53 | head | Glazier | California |
| 20 | Frank Bank | 51 | wife | Operator | California |
| 21 | Mary Larsen | 44 | head | Nurse | Irish Free State |
| 22 | John P. Larsen | 22 | son | Mechanist | Ohio |
| 23 | Mary C. Larsen THIS PERSON | 21 | daughter | — | Pennsylvania |
| 24 | Louis Larsen | 20 | son | — | California |
| 25 | Frank Larsen | 19 | son | Pin Boy | California |
| 26 | Alfred Larsen | 16 | son | — | California |
| 27 | Andrew Larsen | 12 | son | — | California |
| 28 | Lawrence Larsen | 10 | son | — | California |
| 29 | Mary Lee Bittner | 36 | head | — | Missouri |
| 30 | Mark Bowmer | 19 | son | Apprentice | Missouri |
| 31 | Angelo Paggen | 48 | lodger | Gardener | Italy |
| 32 | Agnes Shields | 62 | head | — | Scotland |
| 33 | Robert Jr. Shields | 25 | son | Clerk | Canada English |
| 34 | Eileen Shields | 22 | daughter | Stenographer | Canada English |
| 35 | Jessie Shields | 20 | daughter | Stenographer | Canada English |
| 36 | Chester C. Williams | 47 | head | Salesman | California |
| 37 | Nelcie Williams | 47 | wife | — | Indiana |
| 38 | Bettie Williams | 20 | daughter | Clerk | California |
| 39 | Daniel Scott | 51 | head | Laborer | Canada English |
| 40 | Francis Scott | 20 | son | Auto Painter | 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)