JK
John Knapp — 1940 US Census Record
Linked across censuses1940 United States Federal Census · San-Bernardino-County, California
Our Model Tree links this John Knapp across the 1930 and 1940 US Censuses in San-Bernardino-County, California (XGBoost, ~Confirmed) — first a son (b.~1921), then head of a 6-person household.
Age 19
b. ~1921
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | San-Bernardino-County, California |
| Surname | Knapp |
| Given Name | John R. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Bernardino |
| 1935 Residence (County) | San Bernardino |
| Additional Details | |
| Highest Grade | Hs 4 |
| 1935 Residence | California |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Township / Ward | Rialto City |
| Est. Birth Year | ~1921 |
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 |
|---|---|---|---|---|
| Cora Knapp | Daughter | — | 15 | ~1925 |
| John Knapp | Son | — | 19 | ~1921 |
| George Knapp | Head | — | 62 | ~1878 |
| Harry Knapp | Son | — | 21 | ~1919 |
| George Knapp | Son | — | 22 | ~1918 |
| Cora Knapp | Spouse | — | 58 | ~1882 |
Census Appearances
1930
San Bernardino, …
Son, age 9
San Bernardino, California · implied b. ~1921 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Knapp |
| Given Name | John R |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 9 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Vermont |
| Mother's Birthplace | California |
| Can Read/Write | Yes |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
San-Bernardino-County, California
Son, age 19
San-Bernardino-County, California · implied b. ~1921 — 6 household members
| Surname | Knapp |
| Given Name | John R. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | San Bernardino |
| 1935 Residence (County) | San Bernardino |
| Highest Grade | Hs 4 |
| 1935 Residence | California |
| 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 19 · b. ~1921 · California
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Sibling
George Knapp
Sibling · 1940 · age 22
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Harry Knapp
Sibling · 1940 · age 21
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Cora Knapp
Sibling · 1940 · age 15
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-Bernardino-County, California
Open full size
1940 US Federal Census — San-Bernardino-County, California
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00292-00034)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Troy Harness | 27 | Head | Timekeeper | Arkansas |
| 42 | Cora O. Harness | 21 | Wife | — | Arkansas |
| 43 | Phyllis Harness | 1 | Daughter | — | California |
| 44 | John J. Sweetman | 82 | Head | — | California |
| 45 | Margrett Williams | 62 | Housekeeper | Rancher | California |
| 46 | George B. Knapp | 62 | Head | — | Vermont |
| 47 | Cora O. Knapp | 58 | Wife | — | California |
| 48 | George H. Knapp | 22 | Son | Machine Operator | California |
| 49 | Harry Lee Knapp | 21 | Son | New Work | California |
| 50 | John R. Knapp THIS PERSON | 19 | Son | — | California |
| 51 | Cora Dean Knapp | 15 | Daughter | — | California |
| 52 | Glenn O. Terry | 37 | Head | Machinist | Kansas |
| 53 | Lewis O. Mckehory|Mckehany | 47 | Head | Druggist | California |
| 54 | Blanche D. Mckehory|Mckehany | 47 | Wife | Clerk | Missouri |
| 55 | Wayne F. Mckehory|Mckehany | 21 | Son | — | California |
| 56 | Betty L. Mckehory|Mckehany | 17 | Daughter | — | California |
| 57 | Bertha J. Mckehory|Mckehany | 14 | Daughter | — | California |
| 58 | Milo C. Harris | 75 | Head | Messenger | Vermont |
| 59 | Flora Harris | 75 | Wife | — | Vermont |
| 60 | Edward Basher | 75 | Head | Watch Maker | Ohio |
| 61 | Laura O. Byar | 54 | Head | File Clerk | Illinois |
| 62 | Dora J. Shockley | 71 | Head | Pension | Indiana |
| 63 | Georgia E. Shockley | 65 | Wife | — | Illinois |
| 64 | Ava O. Willis | 52 | Head | Watchman | Missouri |
| 65 | Ida Willis | 49 | Wife | — | Kansas |
| 66 | Margrett Willis | 13 | Daughter | — | Minnesota |
| 67 | Floy Willis | 11 | Daughter | — | Minnesota |
| 68 | Orval Roberts | 57 | Head | Foreman | Arkansas |
| 69 | Cathie O. Roberts | 26 | Daughter | — | Arkansas |
| 70 | Orval Jr. Roberts | 18 | Son | New Worker | Arkansas |
| 71 | Earnest Trump | 47 | Head | New Worker | Missouri |
| 72 | Ione O. Trump | 53 | Wife | Nurse | Missouri |
| 73 | Sarah Robertson | 61 | Lodger | Mental Incompetent | California |
| 74 | Rhoda Foster | 71 | Lodger | — | New York |
| 75 | Margrette Turner | 74 | Lodger | — | Germany |
| 76 | Mary Jones | 69 | Lodger | — | Georgia |
| 77 | George W. Myers | 79 | Head | — | Tenn |
| 78 | Ella O. Myers | 67 | Wife | — | Missouri |
| 79 | Herman Holt-Kamp | 78 | Head | — | Texas |
| 80 | Mary O. Holt-Kamp | 76 | Wife | — | Texas |
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)