JC
John Costello — 1940 US Census Record
Model Tree available1940 United States Federal Census · Suffolk-County, Massachusetts
Our Model Tree links this John Costello across the 1920, 1930 and 1940 US Censuses in Suffolk-County, Massachusetts (XGBoost, ~Confirmed), with identified parents Michael & Thomas — first a son (b.~1914), then head of a 6-person household.
Age 26
b. ~1914
Male
Son
Born: Massachusetts
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Suffolk-County, Massachusetts |
| Surname | Costello |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 26 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston City |
| 1935 Residence (County) | Suffolk |
| Additional Details | |
| Hours Worked | 0 |
| Highest Grade | H 4 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Township / Ward | Boston City |
| Est. Birth Year | ~1914 |
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.
6 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to John | Age | Birth yr |
|---|---|---|---|---|
| Michael Curran | Other | — | 25 | ~1915 |
| Walter Costello | Son | — | 27 | ~1913 |
| Joseph Costello | Son | — | 25 | ~1915 |
| Ellen Costello | Spouse | — | 56 | ~1884 |
| Michael Costello | Head | — | 67 | ~1873 |
| John Costello | Son | — | 26 | ~1914 |
Census Appearances
1920
Suffolk, Massachusetts
Son, age 4
Suffolk, Massachusetts · implied b. ~1916 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Costello |
| Given Name | John W. |
| Relationship to Head | son |
| Sex | M |
| Color / Race | White |
| Age | 4 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Ireland |
| Mother's Birthplace | Ireland |
| Occupation | none |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1930
Suffolk, Massachusetts
Son, age 15
Suffolk, Massachusetts · implied b. ~1915 — 7 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Costello |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 15 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Ireland |
| Mother's Birthplace | Ireland |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Suffolk-County, Massachusetts
Son, age 26
Suffolk-County, Massachusetts · implied b. ~1914 — 6 household members
| Surname | Costello |
| Given Name | John |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 26 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Boston City |
| 1935 Residence (County) | Suffolk |
| Hours Worked | 0 |
| 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 Costello across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father Michael Costello (~0.92 confidence) and father Thomas Costello (~0.92 confidence) and mother Margaret Costello (~0.92 confidence) and mother Ellen Costello (~0.92 confidence) and mother Margaret Costello (~0.92 confidence). The pedigree spans 1 generation with 5 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
Michael Costello
b. ~1873
Source father
● Household
· direct · ~0.92
Father
Thomas Costello
b. ~1876
Source father
● Household
· direct · ~0.92
Mother
Margaret Costello
b. ~1878
Source mother
● Household
· direct · ~0.92
Mother
Ellen Costello
b. ~1884
Source mother
● Household
· direct · ~0.92
Mother
Margaret Costello
b. ~1886
Source mother
● Household
· direct · ~0.92
This person
Anchor record
John Costello
Son · 1940 · age 26 · b. ~1914 · Massachusetts
★ You are viewing this record
Sibling
Joseph Costello
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Walter Costello
Sibling · 1940 · age 27
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 — Suffolk-County, Massachusetts
Open full size
1940 US Federal Census — Suffolk-County, Massachusetts
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-01677-00499)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Robert Hutchings | 5 | Son | — | Massachusetts |
| 2 | Elaine Hutchings | 3 | Daughter | — | Massachusetts |
| 3 | Jannette Hutchings | 1 | Daughter | — | Massachusetts |
| 4 | Michael Costello | 67 | Head | Stationary Fireman | Ireland |
| 5 | Ellen S Costello | 56 | Wife | Housewife | Ireland |
| 6 | Walter Costello | 27 | Son | Salesman | Massachusetts |
| 7 | John Costello THIS PERSON | 26 | Son | — | Massachusetts |
| 8 | Joseph Costello | 25 | Son | — | Massachusetts |
| 9 | Michael Curran | 25 | Nephew | Bar Tender | Ireland |
| 10 | John T Sullivan | 65 | Head | Treasurer | Massachusetts |
| 11 | Margaret M Sullivan | 60 | Wife | Housewife | Massachusetts |
| 12 | Margaret C Sullivan | 31 | Daughter | Teacher | Massachusetts |
| 13 | Mary Sullivan | 22 | Daughter | Teacher | Massachusetts |
| 14 | Catherine White | 69 | Head | Housekeeper | Massachusetts |
| 15 | Galvin | 27 | Head | — | Massachusetts |
| 16 | William Galvin | 28 | Head | Investigator | Massachusetts |
| 17 | Helen E Galvin | 24 | Wife | Housewife | Massachusetts |
| 18 | William Galvin | 2 | Son | — | Massachusetts |
| 19 | Michael Galvin | 1 | Son | — | Massachusetts |
| 20 | John Galvin | 29 | Head | Truck Driver | Massachusetts |
| 21 | Catherine Galvin | 29 | Wife | Housewife | Massachusetts |
| 22 | Margaret Downey | 63 | Head | Housewife | Ireland |
| 23 | Morris J. Downey | 32 | Son | Teacher | Massachusetts |
| 24 | James B. Downey | 23 | Son | New Worker | Massachusetts |
| 25 | Margaret E. Mcgowan | 63 | Head | Housewife | Massachusetts |
| 26 | Mary E. Mcgowan | 57 | Sister | Housewife | Massachusetts |
| 27 | Francis J. Shaw | 42 | Head | Carpenter | Massachusetts |
| 28 | Gertrude M. Shaw | 35 | Wife | Housewife | Massachusetts |
| 29 | Maria Shaw | 13 | Daughter | — | Massachusetts |
| 30 | Francis X. Shaw | 10 | Son | — | Massachusetts |
| 31 | Robert P. Shaw | 7 | Son | — | Massachusetts |
| 32 | Gertrude A. Shaw | 3 | Daughter | — | Massachusetts |
| 33 | Joan P. Shaw | 1 | Daughter | — | Massachusetts |
| 34 | Daniel Kalman | 36 | Head | Porter | Massachusetts |
| 35 | Theresa M. Kalman | 35 | Wife | Housewife | Massachusetts |
| 36 | Douglas Maccook | 24 | Head | Clerk | Massachusetts |
| 37 | Jannette Maccook | 23 | Wife | Housewife | Massachusetts |
| 38 | George Sullivan | 46 | Head | Assigner | Massachusetts |
| 39 | Mary A. Sullivan | 44 | Wife | Housewife | Massachusetts |
| 40 | John Pokorny | 55 | Head | Auto Body Maker | Czechoslovakia |
Pedigree Summary
John + 2 siblings
Gen 1 · 5 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)