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James Mcmahon — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this James Mcmahon across the 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1917), then head of a 12-person household.
Age 23
b. ~1917
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 23 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston |
| 1935 Residence (County) | Suffolk |
| Additional Details | |
| Occupation | Belt man |
| Industry | Bread bakery |
| Class of Worker | PW |
| Hours Worked | 40 |
| Income (1939) | 190 |
| Highest Grade | No 8 |
| 1935 Residence | Massachusetts |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Belt Man |
| Township / Ward | Somerville City |
| Est. Birth Year | ~1917 |
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.
12 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to James | Age | Birth yr |
|---|---|---|---|---|
| Patricia Mcmahon | Daughter | — | 7 | ~1933 |
| Margaret Mcmahon | Daughter | — | 17 | ~1923 |
| Theresa Mcmahon | Daughter | — | 12 | ~1928 |
| Gertrude Mcmahon | Daughter | — | 26 | ~1914 |
| Mildred Mcmahon | Daughter | — | 10 | ~1930 |
| Lillian Mcmahon | Daughter | — | 8 | ~1932 |
| Eileen Mcmahon | Daughter | — | 14 | ~1926 |
| James Mcmahon | Head | — | 48 | ~1892 |
| William Mcmahon | Son | — | 19 | ~1921 |
| James Mcmahon | Son | — | 23 | ~1917 |
| Joseph Mcmahon | Son | — | 21 | ~1919 |
| H Mcmahon | Spouse | — | 48 | ~1892 |
Census Appearances
1930
Middlesex, Massachusetts
Son, age 13
Middlesex, Massachusetts · implied b. ~1917 — 5 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 13 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Ireland-Free State |
| Mother's Birthplace | Ireland-Free State |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 23
Middlesex-County, Massachusetts · implied b. ~1917 — 12 household members
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 23 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston |
| 1935 Residence (County) | Suffolk |
| Occupation | Belt man |
| Industry | Bread bakery |
| Class of Worker | PW |
| Hours Worked | 40 |
| Income (1939) | 190 |
| Highest Grade | No 8 |
| 1935 Residence | Massachusetts |
| 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 James Mcmahon across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
James Mcmahon
Son · 1940 · age 23 · b. ~1917 · Massachusetts
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Sibling
Joseph Mcmahon
Sibling · 1940 · age 21
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Margaret Mcmahon
Sibling · 1940 · age 17
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Eileen Mcmahon
Sibling · 1940 · age 14
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Lillian Mcmahon
Sibling · 1940 · age 8
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Theresa Mcmahon
Sibling · 1940 · age 12
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Gertrude Mcmahon
Sibling · 1940 · age 26
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
William Mcmahon
Sibling · 1940 · age 19
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Patricia Mcmahon
Sibling · 1940 · age 7
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mildred Mcmahon
Sibling · 1940 · age 10
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 — Middlesex-County, Massachusetts
Open full size
1940 US Federal Census — Middlesex-County, Massachusetts
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-01702-00607)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Ronald B. Mader | 44 | Head | Printer | Canada-English |
| 2 | Christine Mader | 40 | Wife | — | Eire |
| 3 | Ronald A. Mader | 7 | Son | — | Massachusetts |
| 4 | Christine M. Mader | 1 | Daughter | — | Massachusetts |
| 5 | Henry Smith | 44 | Head | Butcher | Maine |
| 6 | Lillian Smith | 37 | Wife | — | Canada-English |
| 7 | Dorothy Smith | 16 | Daughter | — | Massachusetts |
| 8 | Marion Smith | 13 | Daughter | — | Massachusetts |
| 9 | Lester Hubbard | 39 | Head | Truck Driver | Canada-French |
| 10 | Margaret Hubbard | 33 | Wife | — | Canada-English |
| 11 | Lester Hubbard | 13 | Son | — | Massachusetts |
| 12 | Shirley Hubbard | 10 | Daughter | — | Massachusetts |
| 13 | James F. Mcmahon | 48 | Head | Mixing-Foreman | Massachusetts |
| 14 | H. Gertrude Mcmahon | 48 | Wife | — | Massachusetts |
| 15 | Gertrude Mcmahon | 26 | Daughter | — | Massachusetts |
| 16 | James Mcmahon THIS PERSON | 23 | Son | Belt Man | Massachusetts |
| 17 | Joseph Mcmahon | 21 | Son | Belt Man | Massachusetts |
| 18 | William Mcmahon | 19 | Son | Checker | Massachusetts |
| 19 | Margaret Mcmahon | 17 | Daughter | New Worker | Massachusetts |
| 20 | Eileen Mcmahon | 14 | Daughter | — | Massachusetts |
| 21 | Theresa Mcmahon | 12 | Daughter | — | Massachusetts |
| 22 | Mildred Mcmahon | 10 | Daughter | — | Massachusetts |
| 23 | Lillian Mcmahon | 8 | Daughter | — | Massachusetts |
| 24 | Patricia Mcmahon | 7 | Daughter | — | Massachusetts |
| 25 | John Ventura | 53 | Head | Upholsterer | Massachusetts |
| 26 | Joanna Ventura | 61 | Wife | — | Portugal |
| 27 | Andrew John X. Ventura | 23 | Nephew | Printer | Massachusetts |
| 28 | Mildred Ashley | 52 | Head | Marker | Massachusetts |
| 29 | Norma Sullivan | 27 | Daughter | — | Massachusetts |
| 30 | Donald Sullivan | 7 | Grandson | — | Massachusetts |
| 31 | Lawrence Cabral | 50 | Lodger | Draftsman | Portugal |
| 32 | Willie Stockbridge | 25 | Head | Jr. Timekeeper | Massachusetts |
| 33 | Catherine Stockbridge | 25 | Wife | — | Massachusetts |
| 34 | Peter J. Purcell | 38 | Head | Yard Foreman | Canada-English |
| 35 | Rita Purcell | 34 | Wife | — | Massachusetts |
| 36 | Edward Purcell | 9 | Son | — | Massachusetts |
| 37 | James Souza | 28 | Head | Machine Operator | Massachusetts |
| 38 | Belinda Souza | 24 | Wife | Radio Tube-Maker | Massachusetts |
| 39 | Emily Souza | 65 | Mother | — | Portugal |
| 40 | Manuel Andrews | 37 | Head | Upholsterer | Portugal |
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)