WK
William Koch — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Los-Angeles-County, California
Our Model Tree links this William Koch across the 1930 and 1940 US Censuses in Los-Angeles-County, California (XGBoost, ~Confirmed) — first a son (b.~1898), then head of a 6-person household.
Age 42
b. ~1898
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Los-Angeles-County, California |
| Surname | Koch |
| Given Name | William B. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 42 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Los Angeles City |
| 1935 Residence (County) | Los Angeles |
| Additional Details | |
| Occupation | Geologist |
| Industry | Geology |
| Class of Worker | OA |
| Hours Worked | 48 |
| Income (1939) | 5293 |
| Highest Grade | C 4 |
| 1935 Residence | Same Place |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Occupation | Geologist |
| Township / Ward | Los Angeles City |
| Est. Birth Year | ~1898 |
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 William | Age | Birth yr |
|---|---|---|---|---|
| Laurence Koch | Son | — | 30 | ~1910 |
| Serena Koch | Head | — | 71 | ~1869 |
| Carlota Koch | Daughter | — | 39 | ~1901 |
| William Koch | Son | — | 42 | ~1898 |
| Rita Urieta | Other | — | 65 | ~1875 |
| Christina Koch | Daughter | — | 33 | ~1907 |
Census Appearances
1930
Los Angeles, …
Son, age 31
Los Angeles, California · implied b. ~1899 — 11 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Koch |
| Given Name | William L. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 31 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Mexico |
| Mother's Birthplace | California |
| Occupation | Manager |
| Industry | Oil production |
| Class of Worker | W |
| Can Read/Write | Yes |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
Los-Angeles-County, California
Son, age 42
Los-Angeles-County, California · implied b. ~1898 — 6 household members
| Surname | Koch |
| Given Name | William B. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 42 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Los Angeles City |
| 1935 Residence (County) | Los Angeles |
| Occupation | Geologist |
| Industry | Geology |
| Class of Worker | OA |
| Hours Worked | 48 |
| Income (1939) | 5293 |
| Highest Grade | C 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 William Koch across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
William Koch
Son · 1940 · age 42 · b. ~1898 · California
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Sibling
Christina Koch
Sibling · 1940 · age 33
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Carlota Koch
Sibling · 1940 · age 39
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Laurence Koch
Sibling · 1940 · age 30
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 — Los-Angeles-County, California
Open full size
1940 US Federal Census — Los-Angeles-County, California
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00416-00509)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | A. George | 29 | Son | Salesman | Michigan |
| 2 | Virginia George | 25 | Daughter | Stenographer | Michigan |
| 3 | Constance E. George | 19 | Daughter | Stock Clerk | Michigan |
| 4 | Stephen Bromley | 41 | Head | Accountant | Illinois |
| 5 | Gertrude A. Bromley | 36 | Wife | — | Illinois |
| 6 | Arthur B. Wier | 56 | Head | Mechanical Engineer | Indiana |
| 7 | Bertha A. Wier | 56 | Wife | — | Indiana |
| 8 | Arthur E. Briggs | 57 | Head | City Councilman | Kansas |
| 9 | Mabel W. Briggs | 56 | Wife | — | Missouri |
| 10 | Carl Jensen | 78 | Head | — | Germany |
| 11 | Emma Jensen | 79 | Wife | — | Germany |
| 12 | Serena O. De Koch | 71 | Head | — | California |
| 13 | William B. Koch THIS PERSON | 42 | Son | Geologist | California |
| 14 | Carlota Koch | 39 | Daughter | Secretary | California |
| 15 | Christina Koch | 33 | Daughter | — | California |
| 16 | Laurence Koch | 30 | Son | Building Contractor | California |
| 17 | Rita Urieta | 65 | Maid | House-Maid | Mexico |
| 18 | Alice M. Brisson | 80 | Head | — | Illinois |
| 19 | Bessie V. Brodeen | 57 | Boarder | — | Iowa |
| 20 | Gladys A. Johnston | 45 | Head | Public School Teacher | Colorado |
| 21 | Joan Johnston | 14 | Daughter | — | California |
| 22 | Carol Johnston | 12 | Daughter | — | California |
| 23 | Anton E. Hintz | 27 | Lodger | Tile Layer | Wisconsin |
| 24 | Harry J. Holdsworth | 70 | Head | — | England |
| 25 | Anna M. Holdsworth | 55 | Wife | — | Canada |
| 26 | James S. Hanson | 28 | Nephew | Board Marker | Oregon |
| 27 | Lawrence E. Shields | 34 | Lodger | Mechanic | Kansas |
| 28 | Charles M. Miller | 25 | Lodger | Produce Buyer | Colorado |
| 29 | Palmer H. Cook | 45 | Head | Fire Insurance Inspector | New York |
| 30 | Dorothy F. Cook | 44 | Wife | — | California |
| 31 | Pauline Ab Cook | 21 | Daughter | — | California |
| 32 | Harriett G. Cook | 16 | Daughter | — | California |
| 33 | Alden R. Weber | 24 | Head | Aircraft Mechanic | Illinois |
| 34 | Edna M. Weber | 24 | Wife | — | Illinois |
| 35 | Trudith Weber | 0 | Daughter | — | California |
| 36 | Margo Lunsford | 24 | Lodger | Addressograph Operator | Florida |
| 37 | John P. Prendergast | 58 | Lodger | Real Estate Salesman | Massachusetts |
| 38 | Walter Burnmann | 54 | Head | Manager | Minnesota |
| 39 | Frances Burnmann | 52 | Wife | — | Kansas |
| 40 | Catherine Burnmann | 22 | Daughter | — | 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)