TM
Thomas Mcmahon — 1940 US Census Record
Model Tree available1940 United States Federal Census · Los-Angeles-County, California
Our Model Tree links this Thomas Mcmahon across the 1920, 1930 and 1940 US Censuses in Los-Angeles-County, California (XGBoost, ~Confirmed), with identified parents Thomas & Thomas — first a son (b.~1916), then head of a 4-person household.
Age 24
b. ~1916
Male
Son
Born: California
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Los-Angeles-County, California |
| Surname | McMahon |
| Given Name | Thomas H. Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 24 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Los Angeles |
| 1935 Residence (County) | Los Angeles |
| Additional Details | |
| Occupation | Optometrist |
| Industry | Private Practice |
| Class of Worker | OA |
| Hours Worked | 40 |
| Income (1939) | 5000 |
| Highest Grade | C 4 |
| 1935 Residence | Same place |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
| Occupation | Optometrist |
| Township / Ward | Los Angeles |
| Est. Birth Year | ~1916 |
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.
4 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Thomas | Age | Birth yr |
|---|---|---|---|---|
| Donald Mcmahon | Son | — | 29 | ~1911 |
| Thos Mcmahon | Head | — | 58 | ~1882 |
| Thomas Mcmahon | Son | — | 24 | ~1916 |
| Janet Mcmahon | Spouse | — | 24 | ~1916 |
Census Appearances
1920
Los Angeles, …
Son, age 3
Los Angeles, California · implied b. ~1917 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | Thomas H. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 3 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1930
Los Angeles, …
Son, age 13
Los Angeles, California · implied b. ~1917 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | Thomas Jr |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 13 |
| Marital Status | Single |
| Birthplace | California |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Can Read/Write | Yes |
| Birth State | California |
| Birth Country | United States |
| Birthplace (normalized) | california |
1940
Los-Angeles-County, California
Son, age 24
Los-Angeles-County, California · implied b. ~1916 — 4 household members
| Surname | McMahon |
| Given Name | Thomas H. Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 24 |
| Marital Status | Single |
| Birthplace | California |
| 1935 Residence (City) | Los Angeles |
| 1935 Residence (County) | Los Angeles |
| Occupation | Optometrist |
| Industry | Private Practice |
| Class of Worker | OA |
| Hours Worked | 40 |
| Income (1939) | 5000 |
| 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 Thomas Mcmahon across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father Thomas Mcmahon (~0.92 confidence) and father Thomas Mcmahon (~0.92 confidence) and father Thos Mcmahon (~0.92 confidence) and mother Janet Mcmahon (~0.50 confidence) and mother Margaret Mcmahon (~0.92 confidence). The pedigree spans 1 generation with 5 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.84
Father
Thomas Mcmahon
b. ~1876
Source father
● Household
· direct · ~0.92
Father
Thomas Mcmahon
b. ~1883
Source father
● Household
· direct · ~0.92
Father
Thos Mcmahon
b. ~1882
Source father
● Household
· direct · ~0.92
Mother
Janet Mcmahon
b. ~1916
Source mother
● Household
· direct · ~0.5
Mother
Margaret Mcmahon
b. ~1888
Source mother
● Household
· direct · ~0.92
This person
Anchor record
Thomas Mcmahon
Son · 1940 · age 24 · b. ~1916 · California
★ You are viewing this record
Sibling
Donald Mcmahon
Sibling · 1940 · age 29
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
26 people indexed on this census page (nara:1940:m-t0627-00416-00511)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 3 | Richard Chapman | 28 | Head | Agent | California |
| 4 | Martha Ann Chapman | 24 | Wife | — | California |
| 5 | Andrew King | 57 | Head | Cutter | Scotland |
| 6 | Marguerite King | 52 | Wife | — | England |
| 7 | Thos. H. Mcmahon | 58 | Head | Optometrist | Massachusetts |
| 8 | Donald G. Mcmahon | 29 | Son | Clerk | California |
| 9 | Thomas H. Jr. Mcmahon THIS PERSON | 24 | Son | Optometrist | California |
| 10 | Janet Mcmahon | 24 | Wife | Stenog. | California |
| 11 | Alvord Alworth | 46 | Head | Manager | Ohio |
| 12 | Josephine Ann Alworth | 45 | Wife | — | Utah |
| 13 | Arthur Raddon Alworth | 20 | Son | — | Idaho |
| 14 | Donald Edward Alworth | 10 | Son | — | California |
| 15 | Delmar Frances Combs | 32 | Lodger | Cutter | Ohio |
| 16 | Sam E. Page | 61 | Head | Elevator Oper. | Iowa |
| 17 | Jennie Page | 60 | Wife | — | Illinois |
| 18 | Ernest A. Rydell | 65 | Lodger | Hardwood | Sweden |
| 19 | Curtis N. Rinehart | 59 | Head | Dentist | U.S.A. |
| 20 | Curtis M. Rinehart | 15 | Son | — | — |
| 21 | Gordon Rinehart | 15 | Son | — | — |
| 22 | Anna M. Rinehart | 54 | Wife | — | — |
| 23 | Mary Washburn | 49 | Lodger | — | Missouri |
| 24 | Allan B. Wilson | 40 | Lodger | Painter | S.A.L. |
| 25 | May B. Wilson | 43 | Lodger | — | America |
| 26 | Byron R. Dexter | 43 | Head | Probate Research | Illinois |
| 27 | Virginia C. Muir | 53 | Wife | — | Arizona |
| 28 | Dorothea B. Butler | 52 | Housekeeper | Housewife | Minnesota |
Pedigree Summary
Thomas + 1 sibling
Gen 1 · 5 parents
~0.84
Max depth 4 (1900–1950 window)
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)