JK
John Knapp — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Marin-County, California
Our Model Tree links this John Knapp across the 1930 and 1940 US Censuses in Marin-County, California (XGBoost, ~Confirmed) — first a son (b.~1922), then head of a 6-person household.
Age 18
b. ~1922
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Marin-County, California |
| Surname | Knapp |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 18 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Ross Town |
| 1935 Residence (County) | Marin |
| Additional Details | |
| Class of Worker | 0 |
| Highest Grade | H 3 |
| 1935 Residence | Same house |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Township / Ward | Ross Town |
| Est. Birth Year | ~1922 |
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.
6 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Elizabeth Knapp | Daughter | — | 23 | ~1917 |
| John Knapp | Son | — | 18 | ~1922 |
| Thomas Knapp | Son | — | 25 | ~1915 |
| William Knapp | Son | — | 21 | ~1919 |
| Edward Knapp | Head | — | 62 | ~1878 |
| Ethel Knapp | Spouse | — | 52 | ~1888 |
Census Appearances
1930
Marin, California
Son, age 8
Marin, California · implied b. ~1922 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Knapp |
| Given Name | John B |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 8 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Pennsylvania |
| Mother's Birthplace | California |
| Occupation | none |
| Can Read/Write | Yes |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
Marin-County, California
Son, age 18
Marin-County, California · implied b. ~1922 — 6 household members
| Surname | Knapp |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 18 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Ross Town |
| 1935 Residence (County) | Marin |
| Class of Worker | 0 |
| Highest Grade | H 3 |
| 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 Knapp across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Knapp
Son · 1940 · age 18 · b. ~1922 · California
★ You are viewing this record
Sibling
William Knapp
Sibling · 1940 · age 21
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Thomas Knapp
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Elizabeth Knapp
Sibling · 1940 · age 23
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 — Marin-County, California
Open full size
1940 US Federal Census — Marin-County, California
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00261-00319)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Wong Mun Git Dessauer | 33 | Servant | Cook | China |
| 42 | Joseph S. Kirby | 56 | Head | Cashier | Virginia |
| 43 | Alma (X) Kirby | 48 | Wife | — | California |
| 44 | Joseph S. Jr. Kirby | 20 | Son | — | California |
| 45 | David B. Kirby | 16 | Son | — | California |
| 46 | William (X) Tuggle | 55 | Head | Broker | Virginia |
| 47 | Hazel Tuggle | 55 | Wife | — | California |
| 48 | Wm H. Tuggle | 25 | Son | Artist | California |
| 49 | Collins Peeler | 40 | Head | — | Virginia |
| 50 | Jesse Riley | 66 | Servant | Cook | Oregon |
| 51 | Clara (X) Riley | 62 | Servant | Cook | Kansas |
| 52 | Edward V. Knapp | 62 | Head | Pathologist | Pennsylvania |
| 53 | Ethel Knapp | 52 | Wife | — | California |
| 54 | Thomas Knapp | 25 | Son | Nurseryman | California |
| 55 | Elizabeth Knapp | 23 | Daughter | Stenographer | California |
| 56 | William (X) Knapp | 21 | Son | — | California |
| 57 | John Knapp THIS PERSON | 18 | Son | — | California |
| 58 | Lester H. Herguedas | 52 | Head | Salesman | California |
| 59 | Gertrude (X) Herguedas | 49 | Wife | — | California |
| 60 | Jean Herguedas | 23 | Daughter | — | California |
| 61 | John Herguedas | 20 | Son | — | California |
| 62 | Arthur Gustafson | 35 | Head | Photo Eng. | California |
| 63 | Lee Gustafson | 34 | Wife | Stenographer | California |
| 64 | Alice F. Jones | 70 | Head | — | California |
| 65 | Vacant Line | None | — | — | — |
| 66 | Ernest H. (X) Denicke | 63 | Head | — | California |
| 67 | Josephine Denicke | 63 | Wife | — | California |
| 68 | Servant Pog Fah | None | M | Private Family | Al |
| 69 | Marie Guerin | 24 | Servant | Housemaid | California |
| 70 | Harvey E. Nelson | 47 | Head | — | Iowa |
| 71 | Julia M. (X) Nelson | 46 | Wife | — | California |
| 72 | Philip S. Molten | 43 | Head | Proprietor | Pennsylvania |
| 73 | Jessie L. (X) Molten | 43 | Wife | Bookkeeper | Mexico |
| 74 | Philip S. Molten | 7 | Son | — | California |
| 75 | Gertrude A. Lee | 72 | Mother-in-law | — | England |
| 76 | Robert R. Macgregor | 42 | Head | Accountant | Scotland |
| 77 | Isabel (X) Macgregor | 36 | Wife | — | California |
| 78 | Isabel L. Macgregor | 12 | Daughter | — | California |
| 79 | Allen Macgregor | 9 | Son | — | California |
| 80 | Viola Macgregor | 31 | Sister | — | Scotland |
Related Census Records
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)