JL
John Leahy — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Worcester-County, Massachusetts
Our Model Tree links this John Leahy across the 1930 and 1940 US Censuses in Worcester-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1928), then head of a 9-person household.
Age 12
b. ~1928
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Worcester-County, Massachusetts |
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | son |
| Sex | M |
| Color / Race | White |
| Age | 12 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Worcester city |
| 1935 Residence (County) | Worcester |
| Additional Details | |
| Highest Grade | 7 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Township / Ward | Worcester City |
| Est. Birth Year | ~1928 |
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.
9 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| John Leahy | Son | — | 12 | ~1928 |
| Stephen Leahy | Head | — | 42 | ~1898 |
| Marie Leahy | Daughter | — | 10 | ~1930 |
| Stephen Leahy | Son | — | 5 | ~1935 |
| Patricia Leahy | Daughter | — | 2 | ~1938 |
| David Leahy | Son | — | 13 | ~1927 |
| Eileen Leahy | Daughter | — | 6 | ~1934 |
| Mary Leahy | Spouse | — | 43 | ~1897 |
| Dora Leahy | Daughter | — | 8 | ~1932 |
Census Appearances
1930
Worcester, Massachusetts
Son, age 1
Worcester, Massachusetts · implied b. ~1929 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 1 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Irish Free State |
| Mother's Birthplace | Irish Free State |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Worcester-County, Massachusetts
Son, age 12
Worcester-County, Massachusetts · implied b. ~1928 — 9 household members
| Surname | Leahy |
| Given Name | John |
| Relationship to Head | son |
| Sex | M |
| Color / Race | White |
| Age | 12 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Worcester city |
| 1935 Residence (County) | Worcester |
| Highest Grade | 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 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 12 · b. ~1928 · Massachusetts
★ You are viewing this record
Sibling
Eileen Leahy
Sibling · 1940 · age 6
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Stephen Leahy
Sibling · 1940 · age 5
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Dora Leahy
Sibling · 1940 · age 8
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Marie Leahy
Sibling · 1940 · age 10
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
David Leahy
Sibling · 1940 · age 13
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Patricia Leahy
Sibling · 1940 · age 2
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 — Worcester-County, Massachusetts
Open full size
1940 US Federal Census — Worcester-County, Massachusetts
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-01717-00515)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Charles H Patterson | 72 | head | Engineer | Massachusetts |
| 2 | Mary E Patterson | 29 | wife | — | Massachusetts |
| 3 | Gerald Patterson | 8 | son | — | Massachusetts |
| 4 | Charles Jr. Patterson | 6 | son | — | Massachusetts |
| 5 | David Patterson | 3 | son | — | Massachusetts |
| 6 | Sol Kessler | 37 | head | Painter | Massachusetts |
| 7 | Sadie Kessler | 37 | wife | — | Massachusetts |
| 8 | Ruth Kessler | 16 | daughter | — | Massachusetts |
| 9 | Sydney Kessler | 14 | son | — | Massachusetts |
| 10 | Gladys Kessler | 11 | daughter | — | Massachusetts |
| 11 | Barbara Kessler | 4 | daughter | — | Massachusetts |
| 12 | Clara Kessler | 3 | daughter | — | Massachusetts |
| 13 | Stephen Leahy | 42 | head | Wire Worker | Ireland FS |
| 14 | Mary Leahy | 43 | wife | — | Ireland FS |
| 15 | David Leahy | 13 | son | — | Massachusetts |
| 16 | John Leahy THIS PERSON | 12 | son | — | Massachusetts |
| 17 | Marie Leahy | 10 | daughter | — | Massachusetts |
| 18 | Dora Leahy | 8 | daughter | — | Massachusetts |
| 19 | Eileen Leahy | 6 | daughter | — | Massachusetts |
| 20 | Stephen Leahy | 5 | son | — | Massachusetts |
| 21 | Patricia Leahy | 2 | daughter | — | Massachusetts |
| 22 | Osborn Seay | 34 | head | Manager | Virginia |
| 23 | Dorothy Seay | 30 | wife | — | Russia |
| 24 | Lorraine Seay | 10 | daughter | — | Rhode Island |
| 25 | Irwin Seay | 8 | son | — | Missouri |
| 26 | Phyllis Seay | 5 | daughter | — | Massachusetts |
| 27 | Patricia Seay | 2 | daughter | — | Massachusetts |
| 28 | Eli Medlinsky | 59 | head | Painter | Russia |
| 29 | Bessie Medlinsky | 55 | wife | — | Russia |
| 30 | Edward Medlinsky | 31 | son | Painter | Massachusetts |
| 31 | David Medlinsky | 28 | son | Salesman | Massachusetts |
| 32 | Abe Medlinsky | 24 | son | Painter | Massachusetts |
| 33 | Sydney Medlinsky | 22 | son | Salesman | Massachusetts |
| 34 | Fay Medlinsky | 25 | daughter | Bookkeeper | Massachusetts |
| 35 | Dorothy Medlinsky | 18 | daughter | — | Massachusetts |
| 36 | Norman Isidell | 32 | head | Truck Driver | Massachusetts |
| 37 | Mildred Isidell | 32 | wife | — | Massachusetts |
| 38 | Dorothy Isidell | 12 | daughter | — | Massachusetts |
| 39 | Norman Isidell | 11 | son | — | Massachusetts |
| 40 | Shirley Isidell | 9 | daughter | — | 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)