JM
James Mcmahon — 1940 US Census Record
Model Tree available1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this James Mcmahon across the 1920, 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed), with identified parents Francis & Francis — first a son (b.~1911), then head of a 5-person household.
Age 29
b. ~1911
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | McMahon |
| Given Name | James T. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 29 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Somerville City |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Occupation | Salesman |
| Industry | Retail Liquor |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 987 |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Salesman |
| Township / Ward | Somerville City |
| Est. Birth Year | ~1911 |
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.
5 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to James | Age | Birth yr |
|---|---|---|---|---|
| Rita Mcmahon | Daughter | — | 25 | ~1915 |
| Dorothy Mcmahon | Daughter | — | 27 | ~1913 |
| Francis Mcmahon | Head | — | 58 | ~1882 |
| James Mcmahon | Son | — | 29 | ~1911 |
| Sarah Mcmahon | Spouse | — | 58 | ~1882 |
Census Appearances
1920
Middlesex, Massachusetts
Son, age 8
Middlesex, Massachusetts · implied b. ~1912 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 8 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Can Read | Yes |
| Can Write | Yes |
| Speaks English | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1930
Middlesex, Massachusetts
Son, age 19
Middlesex, Massachusetts · implied b. ~1911 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James T |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Occupation | Office Boy |
| Industry | Railroad |
| Class of Worker | W |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 29
Middlesex-County, Massachusetts · implied b. ~1911 — 5 household members
| Surname | McMahon |
| Given Name | James T. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 29 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Somerville City |
| 1935 Residence (County) | Middlesex |
| Occupation | Salesman |
| Industry | Retail Liquor |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 987 |
| Highest Grade | Hs 4 |
| 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 James Mcmahon across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father Francis Mcmahon (~0.92 confidence) and father Francis Mcmahon (~0.92 confidence) and mother Sarah Mcmahon (~0.92 confidence) and mother Sarah Mcmahon (~0.92 confidence). The pedigree spans 1 generation with 4 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
Francis Mcmahon
b. ~1882
Source father
● Household
· direct · ~0.92
Father
Francis Mcmahon
b. ~1882
Source father
● Household
· direct · ~0.92
Mother
Sarah Mcmahon
b. ~1882
Source mother
● Household
· direct · ~0.92
Mother
Sarah Mcmahon
b. ~1882
Source mother
● Household
· direct · ~0.92
This person
Anchor record
James Mcmahon
Son · 1940 · age 29 · b. ~1911 · Massachusetts
★ You are viewing this record
Sibling
Rita Mcmahon
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Dorothy Mcmahon
Sibling · 1940 · age 27
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
37 people indexed on this census page (nara:1940:m-t0627-01704-00310)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | David Kratman | 54 | Head | Hairdresser | Russia |
| 2 | Annie Kratman | 56 | Wife | — | Russia |
| 3 | Ruth Kratman | 21 | Daughter | — | Massachusetts |
| 4 | Sam Frommell | 35 | Head | Butcher | Massachusetts |
| 5 | Ray Frommell | 36 | Wife | — | Russia |
| 6 | Elaine Frommell | 14 | Daughter | — | Massachusetts |
| 7 | Beverly Frommell | 2 | Daughter | — | Massachusetts |
| 8 | Morris Kratman | 34 | Head | Clerk | Russia |
| 9 | Rose Kratman | 30 | Wife | — | Massachusetts |
| 10 | John J. Sullivan | 29 | Head | Manager | Massachusetts |
| 11 | Alice M. Sullivan | 26 | Wife | — | Massachusetts |
| 12 | Francis T. Mcmahon | 58 | Head | Clerk | Massachusetts |
| 13 | Sarah Mcmahon | 58 | Wife | — | Massachusetts |
| 14 | James T. Mcmahon THIS PERSON | 29 | Son | Salesman | Massachusetts |
| 15 | Dorothy Mcmahon | 27 | Daughter | Saleslady | Massachusetts |
| 16 | Rita M. Mcmahon | 25 | Daughter | Saleslady | Massachusetts |
| 17 | William Quinn | 36 | Head | Truck Driver | Massachusetts |
| 18 | Helen Quinn | 36 | Wife | — | Massachusetts |
| 19 | Walter Quinn | 10 | Son | — | Massachusetts |
| 20 | Edith Quinn | 7 | Daughter | — | Massachusetts |
| 21 | Joseph Quinn | 5 | Son | — | Massachusetts |
| 22 | William Quinn | 3 | Son | — | Massachusetts |
| 23 | Mary Quinn | 1 | Daughter | — | Massachusetts |
| 24 | James D. Manning | 62 | Head | Undertaker | Massachusetts |
| 25 | Mary Manning | 32 | Daughter | — | Massachusetts |
| 26 | Donald R. Chase | 39 | Head | Salesman | Maine |
| 27 | Mae Chase | 35 | Wife | Forelady | Canada-English |
| 28 | Max Gilman | 63 | Head | Tailor | Ohio |
| 29 | Minnie Gilman | 59 | Wife | — | Ohio |
| 30 | Leo K. Talbot | 27 | Head | Mechanic | Massachusetts |
| 31 | Gertrude M. Talbot | 21 | Wife | — | Massachusetts |
| 32 | Robert Talbot | 0 | Son | — | Massachusetts |
| 33 | Ethel M. Gamble | 42 | Head | — | Massachusetts |
| 34 | Mary Gamble | 23 | Daughter | Nurse | Massachusetts |
| 35 | Maurice P. Miller | 31 | Lodger | Nurse | Massachusetts |
| 36 | Elliott Cochran | 26 | Head | Shipper | Massachusetts |
| 37 | Gwendolyn Cochran | 26 | Wife | — | Canada-English |
Pedigree Summary
James + 2 siblings
Gen 1 · 4 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)