MK
Mary Kirby — 1940 US Census Record
Model Tree available1940 United States Federal Census · Middlesex-County, Massachusetts
Our Model Tree links this Mary Kirby across the 1920, 1930 and 1940 US Censuses in Middlesex-County, Massachusetts (XGBoost, ~Confirmed), with identified parents John & John — first a daughter (b.~1911), then head of a 5-person household.
Age 29
b. ~1911
Female
Daughter
Born: Massachusetts
Married
1940 Census Record Details
| Census Year | 1940 |
| Location | Middlesex-County, Massachusetts |
| Surname | Kirby |
| Given Name | Mary C. |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 29 |
| Marital Status | Married |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Malden City |
| 1935 Residence (County) | Middlesex |
| Additional Details | |
| Class of Worker | 0 |
| Hours Worked | 0 |
| Highest Grade | H-1 |
| 1935 Residence | Same place |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
| Township / Ward | Malden City |
| Est. Birth Year | ~1911 |
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.
5 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| John Kirby | Head | — | 57 | ~1883 |
| John Kirby | Son | — | 27 | ~1913 |
| William Kirby | Other | — | 2 | ~1938 |
| Mary Kirby | Daughter | — | 29 | ~1911 |
| Mary Kirby | Spouse | — | 57 | ~1883 |
Census Appearances
1920
Middlesex, Massachusetts
Daughter, age 9
Middlesex, Massachusetts · implied b. ~1911 — 5 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kirby |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 9 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Can Read | Yes |
| Can Write | Yes |
| Speaks English | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1930
Middlesex, Massachusetts
Daughter, age 19
Middlesex, Massachusetts · implied b. ~1911 — 5 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Kirby |
| Given Name | Mary L |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 19 |
| Marital Status | Single |
| Birthplace | Massachusetts |
| Father's Birthplace | Massachusetts |
| Mother's Birthplace | Massachusetts |
| Occupation | Operator |
| Industry | Telephone |
| Class of Worker | W |
| Can Read/Write | Yes |
| Birth State | Massachusetts |
| Birth Country | United States |
| Birthplace (normalized) | massachusetts |
1940
Middlesex-County, Massachusetts
Daughter, age 29
Middlesex-County, Massachusetts · implied b. ~1911 — 5 household members
| Surname | Kirby |
| Given Name | Mary C. |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 29 |
| Marital Status | Married |
| Birthplace | Massachusetts |
| 1935 Residence (City) | Malden City |
| 1935 Residence (County) | Middlesex |
| Class of Worker | 0 |
| Hours Worked | 0 |
| Highest Grade | H-1 |
| 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 Mary Kirby across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father John Kirby (~0.92 confidence) and father John Kirby (~0.92 confidence) and father John Kirby (~0.92 confidence) and mother Mary Kirby (~0.92 confidence) and mother Mary Kirby (~0.92 confidence). The pedigree spans 1 generation with 5 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
John Kirby
b. ~1880
Source father
● Household
· direct · ~0.92
Father
John Kirby
b. ~1881
Source father
● Household
· direct · ~0.92
Father
John Kirby
b. ~1883
Source father
● Household
· direct · ~0.92
Mother
Mary Kirby
b. ~1883
Source mother
● Household
· direct · ~0.92
Mother
Mary Kirby
b. ~1883
Source mother
● Household
· direct · ~0.92
This person
Anchor record
Mary Kirby
Daughter · 1940 · age 29 · b. ~1911 · Massachusetts
★ You are viewing this record
Sibling
John Kirby
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 — 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-t0627-01608-00230)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Mary Buckley | 64 | Head | — | Ireland |
| 2 | Thomas M. Kelley | 64 | Head | Clerk | Massachusetts |
| 3 | Catherine Kelley | 61 | Wife | — | Massachusetts |
| 4 | Helen Kelley | 30 | Daughter | — | Massachusetts |
| 5 | Agnes Kelley | 24 | Daughter | Clerical | Massachusetts |
| 6 | Thomas W. Kelley | 26 | Son | Policeman | Massachusetts |
| 7 | Johannah Mccarthy | 72 | Head | — | Massachusetts |
| 8 | Timothy Mccarthy | 83 | Brother | — | Massachusetts |
| 9 | Start Of Block 462 End Of Block 461 | None | — | — | — |
| 10 | James Mcdonny | 55 | Head | — | Scotland |
| 11 | Bridget Mcdonny | 52 | Wife | — | Scotland |
| 12 | James A. Mcdonny | 23 | Son | Cutter | Scotland |
| 13 | Gerald A. Mcdonny | 18 | Son | Wpa | Scotland |
| 14 | Harold R. Paynter | 41 | Head | Chauffeur | Canada-English |
| 15 | Myrtle Paynter | 39 | Wife | — | Canada-English |
| 16 | Edward Paynter | 11 | Son | — | Massachusetts |
| 17 | Nancy Paynter | 7 | Daughter | — | Massachusetts |
| 18 | Daniel J. Powell | 63 | Head | — | Massachusetts |
| 19 | Margaret Powell | 57 | Wife | — | Canada-English |
| 20 | Mary O'Neil | 67 | Head | — | Ireland |
| 21 | John F. O'Neil | 42 | Son | — | Michigan |
| 22 | Cornelius F. O'Neil | 33 | Son | Salesman | Massachusetts |
| 23 | Mary O'Neil | 31 | Daughter | Waitress | Massachusetts |
| 24 | Ellen A. Crozier | 79 | Head | — | Rhode Island |
| 25 | Gladys E. Crozier | 57 | Cousin | — | Massachusetts |
| 26 | Charles J. Mccarthy | 59 | Head | Chauffeur | Massachusetts |
| 27 | Catherine Mccarthy | 57 | Wife | — | New York |
| 28 | John F. Nevills | 57 | Son-in-law | Laborer | Massachusetts |
| 29 | Marie Nevills | 20 | Wife | New Worker | Massachusetts |
| 30 | John J. Sullivan | 24 | Head | Reporter | Massachusetts |
| 31 | Mary Sullivan | 24 | Wife | — | Massachusetts |
| 32 | Richard Sullivan | 0 | Son | — | Massachusetts |
| 33 | John W. Kirby | 57 | Head | Painter | Massachusetts |
| 34 | Mary J. Kirby | 57 | Wife | — | Massachusetts |
| 35 | John S. Kirby | 27 | Son | Chauffeur | Massachusetts |
| 36 | Mary C. Kirby THIS PERSON | 29 | Daughter | — | Massachusetts |
| 37 | William Kirby | 2 | Nephew | — | Massachusetts |
| 38 | Edwin Hay | 27 | Head | Laborer | Massachusetts |
| 39 | Helen B. Hay | 26 | Wife | Clerical | Massachusetts |
| 40 | Edwin Jr. Hay | 2 | Son | — | Massachusetts |
Pedigree Summary
Mary + 1 sibling
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)