JC
John Cahill — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this John Cahill across the 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed) — first a son (b.~1921), then head of a 14-person household.
Age 19
b. ~1921
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | Cahill |
| Given Name | John J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Lowell |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Occupation | Laborer |
| Industry | Housing Project |
| Class of Worker | GW |
| Hours Worked | 12 |
| Income (1939) | 988 |
| Highest Grade | H-2 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Occupation | Laborer |
| Township / Ward | Lowell |
| Est. Birth Year | ~1921 |
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.
14 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Elizabeth Cahill | Daughter | — | 5 | ~1935 |
| Dorothy Cahill | Daughter | — | 6 | ~1934 |
| Eleanor Cahill | Daughter | — | 17 | ~1923 |
| Joseph Cahill | Head | — | 42 | ~1898 |
| Edward Cahill | Son | — | 21 | ~1919 |
| Gerald Cahill | Son | — | 9 | ~1931 |
| Helen Cahill | Daughter | — | 16 | ~1924 |
| Walter Cahill | Son | — | 1 | ~1939 |
| Hugh Cahill | Son | — | 8 | ~1932 |
| Theresa Cahill | Daughter | — | 13 | ~1927 |
| Marcella Cahill | Spouse | — | 38 | ~1902 |
| Paul Cahill | Son | — | 11 | ~1929 |
| Mary Cahill | Daughter | — | 18 | ~1922 |
| John Cahill | Son | — | 19 | ~1921 |
Census Appearances
1930
Middlesex, Massachusetts
Son, age 9
Middlesex, Massachusetts · implied b. ~1921 — 5 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Cahill |
| Given Name | John J |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 9 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Irish Free State |
| Mother's Birthplace | Maine |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Son, age 19
Middlesex-County, Massachusetts · implied b. ~1921 — 14 household members
| Surname | Cahill |
| Given Name | John J. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Lowell |
| 1935 Residence (County) | Middlesex |
| Occupation | Laborer |
| Industry | Housing Project |
| Class of Worker | GW |
| Hours Worked | 12 |
| Income (1939) | 988 |
| Highest Grade | H-2 |
| 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 Cahill across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
John Cahill
Son · 1940 · age 19 · b. ~1921 · Massachusetts
★ You are viewing this record
Sibling
Helen Cahill
Sibling · 1940 · age 16
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Elizabeth Cahill
Sibling · 1940 · age 5
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Eleanor Cahill
Sibling · 1940 · age 17
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Paul Cahill
Sibling · 1940 · age 11
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Theresa Cahill
Sibling · 1940 · age 13
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mary Cahill
Sibling · 1940 · age 18
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Hugh Cahill
Sibling · 1940 · age 8
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Dorothy Cahill
Sibling · 1940 · age 6
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Edward Cahill
Sibling · 1940 · age 21
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Gerald Cahill
Sibling · 1940 · age 9
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Walter Cahill
Sibling · 1940 · age 1
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-t0627-01694-00409)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Martha A Gauthier | 25 | Wife | 52 | Massachusetts |
| 2 | Arthur J Gauthier | 3 | Son | — | Massachusetts |
| 3 | Joseph W. Cahill | 42 | Head | Mechanic | Massachusetts |
| 4 | Marcella F Cahill | 38 | Wife | — | Nova Scotia |
| 5 | Edward H Cahill | 21 | Son | Bobbin Boy | Massachusetts |
| 6 | John J. Cahill THIS PERSON | 19 | Son | Laborer | Massachusetts |
| 7 | Mary M. Cahill | 18 | Daughter | New Worker | Massachusetts |
| 8 | Eleanor M. Cahill | 17 | Daughter | New Worker | Massachusetts |
| 9 | Helen M Cahill | 16 | Daughter | — | Massachusetts |
| 10 | Theresa E Cahill | 13 | Daughter | — | Massachusetts |
| 11 | Paul Cahill | 11 | Son | — | Massachusetts |
| 12 | Gerald H. Cahill | 9 | Son | — | Massachusetts |
| 13 | Hugh P. Cahill | 8 | Son | — | Massachusetts |
| 14 | Dorothy Cahill | 6 | Daughter | — | Massachusetts |
| 15 | Elizabeth A Cahill | 5 | Daughter | — | Massachusetts |
| 16 | Walter Cahill | 1 | Son | — | Massachusetts |
| 17 | Alice M. Bizzell | 75 | Head | — | England |
| 18 | John Grenciewicz | 77 | Head | — | Poland |
| 19 | Anthony Mcauliffe | 70 | Head | — | Armenia |
| 20 | Antonio Coimbra | 54 | Head | Tacker | Portugal |
| 21 | Carolina Coimbra | 48 | Wife | — | Portugal |
| 22 | Philomena Coimbra | 22 | Daughter | Seamstress | Massachusetts |
| 23 | Florence Coimbra | 19 | Daughter | New Worker | Massachusetts |
| 24 | Anthony Coimbra | 11 | Son | — | Massachusetts |
| 25 | Francis Coimbra | 9 | Son | — | Massachusetts |
| 26 | James Arthur | 39 | Head | Machinist | Nova Scotia |
| 27 | Catherine Arthur | 46 | Wife | — | Ireland |
| 28 | James Arthur | 10 | Son | — | Massachusetts |
| 29 | Florence Arthur | 9 | Daughter | — | Massachusetts |
| 30 | Geraldine Arthur | 7 | Daughter | — | Massachusetts |
| 31 | John A. Shea | 73 | Head | — | Connecticut |
| 32 | William Shea | 30 | Son | Mechanic | Massachusetts |
| 33 | John Jr. Shea | 25 | Son | — | Massachusetts |
| 34 | George Gentle | 46 | Head | Laborer | Massachusetts |
| 35 | Mary A. Gentle | 51 | Wife | — | Massachusetts |
| 36 | Harold Gentle | 26 | Son | Tacker | Massachusetts |
| 37 | Thomas Ab Gentle | 21 | Son | — | Massachusetts |
| 38 | James Gentle | 14 | Son | — | Massachusetts |
| 39 | Rita Gentle | 12 | Daughter | — | Massachusetts |
| 40 | Stephen Burns | 70 | Head | — | 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)