JM
John Mcmahon — 1940 US Census Record
Model Tree available1940 United States Federal Census · Suffolk-County, Massachusetts
Our Model Tree links this John Mcmahon across the 1920, 1930 and 1940 US Censuses in Suffolk-County, Massachusetts (XGBoost, ~Confirmed), with identified parents John & John — first a head (b.~1919), then head of a 3-person household.
Age 21
b. ~1919
Male
Head
Born: Massachusetts
Married
1940 Census Record Details
| Census Year | 1940 |
| Location | Suffolk-County, Massachusetts |
| Surname | MCMAHON |
| Given Name | John |
| Relationship to Head | Head |
| Sex | M |
| Color / Race | White |
| Age | 21 |
| Marital Status | Married |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston |
| 1935 Residence (County) | Suffolk |
| Additional Details | |
| Occupation | Salesman |
| Industry | ICE-COAL |
| Class of Worker | OA |
| Hours Worked | 60 |
| Income (1939) | 540 |
| Highest Grade | No 12 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Salesman |
| Township / Ward | Boston |
| 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.
3 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Gertrude Mcmahon | Daughter | — | 1 | ~1939 |
| John Mcmahon | Head | — | 21 | ~1919 |
| Martha Mcmahon | Spouse | — | 20 | ~1920 |
Census Appearances
1920
Suffolk, Massachusetts
Son, age
Suffolk, Massachusetts · implied b. ~1920 — 3 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | John Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 0 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1930
Suffolk, Massachusetts
Son, age 10
Suffolk, Massachusetts · implied b. ~1920 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | John A. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Occupation | none |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Suffolk-County, Massachusetts
Head, age 21
Suffolk-County, Massachusetts · implied b. ~1919 — 3 household members
| Surname | MCMAHON |
| Given Name | John |
| Relationship to Head | Head |
| Sex | M |
| Color / Race | White |
| Age | 21 |
| Marital Status | Married |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston |
| 1935 Residence (County) | Suffolk |
| Occupation | Salesman |
| Industry | ICE-COAL |
| Class of Worker | OA |
| Hours Worked | 60 |
| Income (1939) | 540 |
| Highest Grade | No 12 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
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 Mcmahon across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father John Mcmahon (~0.92 confidence) and father John Mcmahon (~0.92 confidence) and mother Margaret Mcmahon (~0.92 confidence). The pedigree spans 1 generation with 3 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
John Mcmahon
b. ~1895
Source father
● Household
· direct · ~0.92
Father
John Mcmahon
b. ~1896
Source father
● Household
· direct · ~0.92
Mother
Margaret Mcmahon
b. ~1898
Source mother
● Household
· direct · ~0.92
This person
Anchor record
John Mcmahon
Head · 1940 · age 21 · b. ~1919 · Massachusetts
★ You are viewing this record
Confirmed / household (~0.90+)
Probable / derived (~0.65–0.89)
Candidate (<0.65, unverified)
Original Census Page
1940 US Federal Census — Suffolk-County, Massachusetts
Open full size
1940 US Federal Census — Suffolk-County, Massachusetts
Page Contents
18 people indexed on this census page (nara:1940:m-t0627-01668-00153)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Margaret Roland | 64 | Head | — | Poland |
| 42 | Mathew Thompson | 67 | Lodger | Salesman | Poland |
| 43 | Thomas Cook | 27 | Head | Fish Cutter | Massachusetts |
| 44 | Mary Cook | 26 | Wife | — | Massachusetts |
| 45 | John Cook | 1 | Son | — | Massachusetts |
| 46 | James Kilroy | 49 | Head | Painter | Massachusetts |
| 47 | Mary Kilroy | 47 | Wife | — | Massachusetts |
| 48 | Mary Kilroy | 25 | Daughter | Packer | Massachusetts |
| 49 | Thomas Kilroy | 22 | Son | Clerk | Massachusetts |
| 50 | John Kilroy | 21 | Son | Laborer | Massachusetts |
| 51 | Joseph Kilroy | 20 | Son | New Worker | Massachusetts |
| 52 | William Kedford | 55 | Head | Laborer | Massachusetts |
| 53 | Mary Kedford | 26 | Daughter | Sorter | Massachusetts |
| 54 | William Kedford | 10 | Son | — | Massachusetts |
| 55 | John Mcmahon THIS PERSON | 21 | Head | Salesman | Massachusetts |
| 56 | Martha Mcmahon | 20 | Wife | — | Massachusetts |
| 57 | Gertrude Mcmahon | 1 | Daughter | — | Massachusetts |
| 58 | Bedros Asadorian | 45 | Head | Salesman | Armenia |
Pedigree Summary
John
Gen 1 · 3 parents
~0.92
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)