WM
William Mahoney — 1940 US Census Record
Model Tree available1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this William Mahoney across the 1920, 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed), with identified parents John & Catherine — first a son (b.~1919), then head of a 11-person household.
Age 21
b. ~1919
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | Mahoney |
| Given Name | William J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Belmont Town |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Occupation | Transportation clerk |
| Industry | Rail Road |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 1090 |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Transportation Clerk |
| Township / Ward | Belmont Town |
| 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.
11 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to William | Age | Birth yr |
|---|---|---|---|---|
| Ruth Mahoney | Daughter | — | 15 | ~1925 |
| Catherine Mahoney | Head | — | 52 | ~1888 |
| William Mahoney | Son | — | 21 | ~1919 |
| Alan Mahoney | Son | — | 16 | ~1924 |
| Maura Mahoney | Daughter | — | 13 | ~1927 |
| Paul Mahoney | Son | — | 25 | ~1915 |
| Esther Kelly | Other | — | 41 | ~1899 |
| Robert Mahoney | Son | — | 19 | ~1921 |
| Richard Mahoney | Son | — | 23 | ~1917 |
| Eleanor Kelly | Daughter | — | 17 | ~1923 |
| John Mahoney | Son | — | 26 | ~1914 |
Census Appearances
1920
Middlesex, Massachusetts
Son, age
Middlesex, Massachusetts · implied b. ~1920 — 8 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Mahoney |
| Given Name | William |
| 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
Middlesex, Massachusetts
Son, age 11
Middlesex, Massachusetts · implied b. ~1919 — 12 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Mahoney |
| Given Name | William |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 11 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 21
Middlesex-County, Massachusetts · implied b. ~1919 — 11 household members
| Surname | Mahoney |
| Given Name | William J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 21 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Belmont Town |
| 1935 Residence (County) | Middlesex |
| Occupation | Transportation clerk |
| Industry | Rail Road |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 1090 |
| 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 William Mahoney across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father John Mahoney (~0.92 confidence) and mother Catherine Mahoney (~0.92 confidence) and father James Mahoney (~0.92 confidence). The pedigree spans 1 generation with 3 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
John Mahoney
b. ~1879
Source father
● Household
· direct · ~0.92
Mother
Catherine Mahoney
b. ~1888
Source mother
● Household
· direct · ~0.92
Father
James Mahoney
b. ~1888
Source father
● Household
· direct · ~0.92
This person
Anchor record
William Mahoney
Son · 1940 · age 21 · b. ~1919 · Massachusetts
★ You are viewing this record
Sibling
Eleanor Kelly
Sibling · 1940 · age 17
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Maura Mahoney
Sibling · 1940 · age 13
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Paul Mahoney
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Alan Mahoney
Sibling · 1940 · age 16
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Robert Mahoney
Sibling · 1940 · age 19
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
John Mahoney
Sibling · 1940 · age 26
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Ruth Mahoney
Sibling · 1940 · age 15
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Richard Mahoney
Sibling · 1940 · age 23
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-t0627-01602-00996)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Theresa Fitzgerald | 8 | daughter | — | Massachusetts |
| 42 | Catherine Mahoney | 52 | Head | — | Massachusetts |
| 43 | John F. Mahoney | 26 | Son | Library Clerk | Massachusetts |
| 44 | Paul T. Mahoney | 25 | Son | Actuary Clerk | Massachusetts |
| 45 | Richard C. Mahoney | 23 | Son | — | Massachusetts |
| 46 | William J. Mahoney THIS PERSON | 21 | Son | Transportation Clerk | Massachusetts |
| 47 | Robert E. Mahoney | 19 | Son | — | Massachusetts |
| 48 | Alan D. Mahoney | 16 | Son | — | Massachusetts |
| 49 | Ruth C. Mahoney | 15 | daughter | — | Massachusetts |
| 50 | Maura A. Mahoney | 13 | daughter | — | Massachusetts |
| 51 | Esther M. Kelly | 41 | house-keeper | Housekeeper | Massachusetts |
| 52 | Eleanor Kelly | 17 | daughter | — | Massachusetts |
| 53 | Arthur E. Hough | 59 | Head | Town Clerk | Massachusetts |
| 54 | Mary G. Hough | 58 | wife | — | Massachusetts |
| 55 | Gilla A. Currier | 85 | mother-in-law | — | Massachusetts |
| 56 | Warren Reid | 49 | Head | Telephone Engineer | Massachusetts |
| 57 | Warren H. Jr. Reid | 20 | son | — | Massachusetts |
| 58 | Robert Reid | 18 | son | — | Massachusetts |
| 59 | Alfred S. Ward | 30 | Head | Naval Officer | Alabama |
| 60 | Winona Ward | 28 | wife | — | Washington |
| 61 | Marion Ward | 1 | daughter | — | Maryland |
| 62 | William F. Sunderlin | 50 | Head | Traveling Salesman | New York |
| 63 | Helen Sunderlin | 45 | wife | — | New York |
| 64 | Louise Sunderlin | 19 | daughter | — | New York |
| 65 | David B. Sunderlin | 17 | son | — | New York |
| 66 | William Sunderlin | 6 | son | — | New York |
| 67 | Stanley Nowak | 39 | Head | Medical Doctor | Massachusetts |
| 68 | Helen Nowak | 38 | wife | — | Poland |
| 69 | Theresa Nowak | 12 | daughter | — | Massachusetts |
| 70 | Joan Nowak | 8 | daughter | — | Massachusetts |
| 71 | Stanley Jr. Nowak | 6 | son | — | Massachusetts |
| 72 | Charles Bonanno | 38 | Head | President | Massachusetts |
| 73 | Carmen Bonanno | 36 | wife | — | Massachusetts |
| 74 | Charles Bonanno | 4 | son | — | Massachusetts |
| 75 | Rosa Bonanno | 0 | daughter | — | Massachusetts |
| 76 | Sarkis Atamian | 59 | Head | President | Armenia |
| 77 | Lillian Atamian | 50 | wife | — | Armenia |
| 78 | Harry Atamian | 31 | son | Vice-President | Massachusetts |
| 79 | Arpie Atamian | 29 | daughter | — | Massachusetts |
| 80 | Lucy Atamian | 23 | daughter | — | Massachusetts |
Pedigree Summary
William + 8 siblings
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)