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John Mcmahon — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this John Mcmahon across the 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1926), then head of a 10-person household.
Age 14
b. ~1926
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | McMahon |
| Given Name | John M. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 14 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Bedford |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Highest Grade | G 7 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Township / Ward | Bedford |
| Est. Birth Year | ~1926 |
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.
10 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Mary Mcmahon | Daughter | — | 16 | ~1924 |
| Theresa Mcmahon | Daughter | — | 1 | ~1939 |
| Helen Mcmahon | Daughter | — | 10 | ~1930 |
| Martin Mcmahon | Head | — | 52 | ~1888 |
| Paul Mcmahon | Son | — | 12 | ~1928 |
| James Mcmahon | Son | — | 8 | ~1932 |
| William Mcmahon | Son | — | 15 | ~1925 |
| Francis Mcmahon | Son | — | 18 | ~1922 |
| John Mcmahon | Son | — | 14 | ~1926 |
| Mary Mcmahon | Spouse | — | 47 | ~1893 |
Census Appearances
1930
Middlesex, Massachusetts
Son, age 3
Middlesex, Massachusetts · implied b. ~1927 — 7 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 3 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 14
Middlesex-County, Massachusetts · implied b. ~1926 — 10 household members
| Surname | McMahon |
| Given Name | John M. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 14 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Bedford |
| 1935 Residence (County) | Middlesex |
| Highest Grade | G 7 |
| 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 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Mcmahon
Son · 1940 · age 14 · b. ~1926 · Massachusetts
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Sibling
James Mcmahon
Sibling · 1940 · age 8
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Paul Mcmahon
Sibling · 1940 · age 12
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Theresa Mcmahon
Sibling · 1940 · age 1
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Helen Mcmahon
Sibling · 1940 · age 10
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
William Mcmahon
Sibling · 1940 · age 15
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Mcmahon
Sibling · 1940 · age 16
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Francis Mcmahon
Sibling · 1940 · age 18
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-t0627-01602-00518)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Geraldine Winchelbaugh | 29 | Daughter | Dietician | Massachusetts |
| 42 | Carol Ann Winchelbaugh | 2 | Daughter | — | Maine |
| 43 | William J. Martines | 39 | Head | Milk Dealer | Massachusetts |
| 44 | Margaret Martines | 38 | Wife | — | Massachusetts |
| 45 | Frank Martines | 17 | Son | — | Massachusetts |
| 46 | William J. Jr. Martines | 15 | Son | — | Massachusetts |
| 47 | Anthony Lentine | 21 | Son-in-law | Laborer | Massachusetts |
| 48 | Mary F. Lentine | 19 | Daughter | General Clerical | Massachusetts |
| 49 | Alice Sullivan | 11 | Lodger | — | Massachusetts |
| 50 | Martin Mcmahon | 52 | Head | Landscape Gardener | Massachusetts |
| 51 | Mary E. Mcmahon | 47 | Wife | — | Massachusetts |
| 52 | Francis B. Mcmahon | 18 | Son | Mechanic'S Helper | Massachusetts |
| 53 | Mary A. Mcmahon | 16 | Daughter | — | Massachusetts |
| 54 | William T. Mcmahon | 15 | Son | — | Massachusetts |
| 55 | John M. Mcmahon THIS PERSON | 14 | Son | — | Massachusetts |
| 56 | Paul Mcmahon | 12 | Son | — | Massachusetts |
| 57 | Helen Mcmahon | 10 | Daughter | — | Massachusetts |
| 58 | James J. Mcmahon | 8 | Son | — | Massachusetts |
| 59 | Theresa A. Mcmahon | 1 | Daughter | — | Massachusetts |
| 60 | Charles A. Shelton | 68 | Head | Superintendent | Massachusetts |
| 61 | Alma R. Shelton | 56 | Wife | — | Massachusetts |
| 62 | Richard B. Jr. Bridgeman | 39 | Head | Medical Officer | Missouri |
| 63 | Wilka Bridgeman | 38 | Wife | — | Missouri |
| 64 | Richard B. 3Rd Bridgeman | 9 | Son | — | Missouri |
| 65 | Mary Manthe | 59 | Head | — | Massachusetts |
| 66 | John Manthe | 23 | Son | Attendant | Massachusetts |
| 67 | Henrietta Manthe | 18 | Daughter | — | Massachusetts |
| 68 | Madeline Manthe | 16 | Daughter | — | Massachusetts |
| 69 | Mary Meagher | 78 | Head | — | Massachusetts |
| 70 | Theodore Meagher | 46 | Son | Carpenter | Massachusetts |
| 71 | Madeline Meagher | 40 | Daughter | General Clerk | Massachusetts |
| 72 | Elizabeth A. Drake | 46 | Head | Office Manager | Maine |
| 73 | Carrie M. Drake | 68 | Mother | — | Maine |
| 74 | Clarence Morton | 38 | Head | Occupational Therapy Attendant | Massachusetts |
| 75 | Helen Morton | 29 | Wife | — | Massachusetts |
| 76 | Norman Morton | 3 | Son | — | Massachusetts |
| 77 | Lawrence Morton | 2 | Son | — | Massachusetts |
| 78 | John M. Harrington | 68 | Head | Laborer | Massachusetts |
| 79 | Bertha L. Harrington | 65 | Wife | — | Massachusetts |
| 80 | Samuel F. Jones | 40 | Head | Bank Clerk | Massachusetts |
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)