JL
John Leahy — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this John Leahy across the 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1916), then head of a 12-person household.
Age 24
b. ~1916
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 24 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Somerville |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Occupation | Metallurgist |
| Class of Worker | PW |
| Hours Worked | 40 |
| Income (1939) | 1200 |
| Highest Grade | H 4 |
| 1935 Residence | Same Place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Metallurgist |
| Township / Ward | Somerville |
| Est. Birth Year | ~1916 |
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 John | Age | Birth yr |
|---|---|---|---|---|
| Sarah Leahy | Spouse | — | 54 | ~1886 |
| Edward Leahy | Son | — | 34 | ~1906 |
| Thomas Leahy | Son | — | 20 | ~1920 |
| Albert Leahy | Head | — | 56 | ~1884 |
| Joseph Leahy | Son | — | 33 | ~1907 |
| Albert Leahy | Son | — | 29 | ~1911 |
| Loretta Leahy | Daughter | — | 31 | ~1909 |
| Rita Leahy | Daughter | — | 35 | ~1905 |
| Catherine Leahy | Daughter | — | 19 | ~1921 |
| Margaret Leahy | Daughter | — | 25 | ~1915 |
| John Leahy | Son | — | 24 | ~1916 |
| Robert Leahy | Son | — | 27 | ~1913 |
Census Appearances
1930
Norfolk, Massachusetts
Son, age 13
Norfolk, Massachusetts · implied b. ~1917 — 8 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 13 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Irish Free State |
| Mother's Birthplace | Massachusetts |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 24
Middlesex-County, Massachusetts · implied b. ~1916 — 12 household members
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 24 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Somerville |
| 1935 Residence (County) | Middlesex |
| Occupation | Metallurgist |
| Class of Worker | PW |
| Hours Worked | 40 |
| Income (1939) | 1200 |
| Highest Grade | H 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 John Leahy across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Leahy
Son · 1940 · age 24 · b. ~1916 · Massachusetts
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Sibling
Robert Leahy
Sibling · 1940 · age 27
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Margaret Leahy
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Thomas Leahy
Sibling · 1940 · age 20
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Joseph Leahy
Sibling · 1940 · age 33
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Edward Leahy
Sibling · 1940 · age 34
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Rita Leahy
Sibling · 1940 · age 35
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Albert Leahy
Sibling · 1940 · age 29
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Catherine Leahy
Sibling · 1940 · age 19
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Loretta Leahy
Sibling · 1940 · age 31
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-t0627-01704-00038)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Thomas J. Walsh | 21 | Nephew | New Worker | Massachusetts |
| 2 | James Drury | 25 | Head | Bellman | Massachusetts |
| 3 | Eleanor Drury | 24 | Wife | — | Massachusetts |
| 4 | Patricia Drury | 2 | Daughter | — | Massachusetts |
| 5 | Marion Young | 54 | Head | Landlady | Massachusetts |
| 6 | Francis Grant | 21 | Lodger | Laborer | Massachusetts |
| 7 | Francis Gardner | 18 | Lodger | — | Massachusetts |
| 8 | Walter Georges | 15 | Lodger | — | Massachusetts |
| 9 | Joseph Gimmini | 14 | Lodger | — | Massachusetts |
| 10 | Norman Brown | 12 | Lodger | — | Massachusetts |
| 11 | Henry Brown | 10 | Lodger | — | Massachusetts |
| 12 | Timothy Gimmini | 10 | Lodger | — | Massachusetts |
| 13 | Anthony Gardone | 10 | Lodger | — | Massachusetts |
| 14 | John Cavaleria | 11 | Lodger | — | Massachusetts |
| 15 | Albert M. Leahy | 56 | Head | Master Mechanic | Massachusetts |
| 16 | Sarah C. Leahy | 54 | Wife | — | Massachusetts |
| 17 | Rita Leahy | 35 | Daughter | — | Massachusetts |
| 18 | Edward J. Leahy | 34 | Son | Typist | Massachusetts |
| 19 | Joseph Leahy | 33 | Son | — | Massachusetts |
| 20 | Loretta Leahy | 31 | Daughter | Telephone Op. | Massachusetts |
| 21 | Albert Leahy | 29 | Son | Truck Driver | Massachusetts |
| 22 | Robert Leahy | 27 | Son | Counterman | Massachusetts |
| 23 | Margaret Leahy | 25 | Daughter | Bookkeeper | Massachusetts |
| 24 | John Leahy THIS PERSON | 24 | Son | Metallurgist | Massachusetts |
| 25 | Thomas Leahy | 20 | Son | — | Massachusetts |
| 26 | Catherine Leahy | 19 | Daughter | — | Massachusetts |
| 27 | George T. Latimer | 75 | Head | — | Canada English |
| 28 | Eva Q. Latimer | 71 | Wife | — | Canada English |
| 29 | Mina A. Latimer | 72 | Sister | — | Canada English |
| 30 | Paul B. Graves | 31 | Head | Accountant | Massachusetts |
| 31 | Ruth F. Graves | 30 | Wife | — | Massachusetts |
| 32 | Jean M. Hyde | 72 | Head | — | Vermont |
| 33 | Leon Hyde | 44 | Son | — | Vermont |
| 34 | Alice E. Engle | 66 | Head | — | New Hampshire |
| 35 | Alice E. O'Meara | 25 | Daughter | — | Massachusetts |
| 36 | John F. O'Meara | 5 | Nephew | — | Massachusetts |
| 37 | Clarence Dadson | 54 | Head | Lineman | New York |
| 38 | Mabel Dadson | 47 | Wife | — | Canada English |
| 39 | Doris Florence Dadson | 19 | Daughter | — | Canada English |
| 40 | John J. Mccarthy | 30 | Head | Printer | 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)