WM
William Mcmahon — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this William Mcmahon across the 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1930), then head of a 11-person household.
Age 10
b. ~1930
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | McMahon |
| Given Name | William J. |
| Relationship to Head | son |
| Sex | M |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Newton City |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Hours Worked | 0 |
| Income (1939) | 0 |
| Highest Grade | C 3 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Township / Ward | Newton City |
| Est. Birth Year | ~1930 |
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.
11 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to William | Age | Birth yr |
|---|---|---|---|---|
| Shirley Mcmahon | Daughter | — | 1 | ~1939 |
| Mary Boyd | Daughter | — | 13 | ~1927 |
| Ralph Boyd | Other | — | 40 | ~1900 |
| Helena Boyd | Daughter | — | 9 | ~1931 |
| Anna Mcmahon | Spouse | — | 35 | ~1905 |
| Florence Boyd | Spouse | — | 22 | ~1918 |
| James Mcmahon | Head | — | 40 | ~1900 |
| Dorothy Mcmahon | Daughter | — | 12 | ~1928 |
| Edward Mcmahon | Son | — | 14 | ~1926 |
| William Mcmahon | Son | — | 10 | ~1930 |
| James Mcmahon | Son | — | 17 | ~1923 |
Census Appearances
1930
Middlesex, Massachusetts
Son, age
Middlesex, Massachusetts · implied b. ~1930 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | William E. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 0 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Can Read/Write | No |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 10
Middlesex-County, Massachusetts · implied b. ~1930 — 11 household members
| Surname | McMahon |
| Given Name | William J. |
| Relationship to Head | son |
| Sex | M |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Newton City |
| 1935 Residence (County) | Middlesex |
| Hours Worked | 0 |
| Income (1939) | 0 |
| Highest Grade | C 3 |
| 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 William Mcmahon across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
William Mcmahon
Son · 1940 · age 10 · b. ~1930 · Massachusetts
★ You are viewing this record
Sibling
James Mcmahon
Sibling · 1940 · age 17
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Helena Boyd
Sibling · 1940 · age 9
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Dorothy Mcmahon
Sibling · 1940 · age 12
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Edward Mcmahon
Sibling · 1940 · age 14
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Shirley Mcmahon
Sibling · 1940 · age 1
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Boyd
Sibling · 1940 · age 13
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-t0627-01614-00426)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Harry H. Hazeldine | 38 | head | Editor | England |
| 2 | Myrtle S. Hazeldine | 41 | wife | — | Illinois |
| 3 | Willard J. Ball | 46 | roomer | Salesman | Massachusetts |
| 4 | Catherine S. Ball | 44 | roomer | — | Massachusetts |
| 5 | Mary E. Greer | 68 | head | — | Ohio |
| 6 | Maynard Grace S. Greer | 64 | sister | — | Ohio |
| 7 | James J. Mcmahon | 40 | head | Laborer | Massachusetts |
| 8 | Anna M. Mcmahon | 35 | wife | — | Massachusetts |
| 9 | James M. Mcmahon | 17 | son | — | Massachusetts |
| 10 | Edward J. Mcmahon | 14 | son | — | Massachusetts |
| 11 | Dorothy A. Mcmahon | 12 | daughter | — | Massachusetts |
| 12 | William J. Mcmahon THIS PERSON | 10 | son | — | Massachusetts |
| 13 | Shirley A. Mcmahon | 1 | daughter | — | Massachusetts |
| 14 | Ralph S. Boyd | 40 | roomer | Truck Driver | Massachusetts |
| 15 | Florence F. Boyd | 22 | wife | — | Massachusetts |
| 16 | Mary F. Boyd | 13 | daughter | — | Massachusetts |
| 17 | Helena F. Boyd | 9 | daughter | — | Massachusetts |
| 18 | Margaret G. Murphy | 73 | head | — | Ireland |
| 19 | John E. Mcgrath | 38 | cousin | Salesman | Massachusetts |
| 20 | Henry M. Coppinger | 63 | head | — | Massachusetts |
| 21 | Ellen E. Coppinger | 47 | daughter | Clerk | Massachusetts |
| 22 | Thomas H. Mccourt | 55 | head | Accountant | England |
| 23 | Mary S. Mccourt | 57 | wife | — | Massachusetts |
| 24 | Joseph G. Morris | 50 | head | Guard | Vermont |
| 25 | Elizabeth J. Morris | 50 | wife | — | Massachusetts |
| 26 | Olive D. Leach | 55 | head | — | Massachusetts |
| 27 | Sidney S. Leach | 59 | husband | — | Quebec |
| 28 | Helen H. Farrell | 51 | head | Teacher | Massachusetts |
| 29 | Edward E. Farrell | 52 | son | — | Massachusetts |
| 30 | Margaret L. Farrell | 24 | niece | Dressmaker | Massachusetts |
| 31 | Elmer E. Butler | 60 | head | Editor | Nova Scotia |
| 32 | Addie Butler | 54 | wife | — | New Brunswick |
| 33 | David W. Kean | 64 | head | Freight Conductor | Massachusetts |
| 34 | Lenore J. Kean | 60 | wife | — | Massachusetts |
| 35 | Lois E. Kean | 34 | daughter | Stenographer | Massachusetts |
| 36 | Jane Kean | 15 | daughter | — | Massachusetts |
| 37 | Ernest N. Hoyt | 53 | head | Musician | Massachusetts |
| 38 | Clara B. Hoyt | 55 | wife | — | Massachusetts |
| 39 | John W. Quinn | 22 | head | Painter | Massachusetts |
| 40 | Marie E. Quinn | 20 | wife | — | Massachusetts |
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)