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Mary Mcmahon — 1940 US Census Record
Model Tree available1940 United States Federal Census · Washington-County, Pennsylvania
Our Model Tree links this Mary Mcmahon across the 1920, 1930 and 1940 US Censuses in Washington-County, Pennsylvania (XGBoost, ~Confirmed), with identified parents James & Elizabeth — first a daughter (b.~1903), then head of a 4-person household.
Age 37
b. ~1903
Female
Daughter
Born: Pennsylvania
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Washington-County, Pennsylvania |
| Surname | McMahon |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 37 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | Monongahela City |
| 1935 Residence (County) | Washington |
| Additional Details | |
| Occupation | Clerk |
| Industry | Retail Grocery Store |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 588 |
| Highest Grade | No 8 |
| 1935 Residence | Same place |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
| Occupation | Clerk |
| Township / Ward | Monongahela City |
| Est. Birth Year | ~1903 |
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.
4 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to Mary | Age | Birth yr |
|---|---|---|---|---|
| Mary Mcmahon | Daughter | — | 37 | ~1903 |
| Thelma Mcmahon | Daughter | — | 32 | ~1908 |
| Grace Mcmahon | Daughter | — | 36 | ~1904 |
| Elizabeth Mcmahon | Head | — | 71 | ~1869 |
Census Appearances
1920
Washington, Pennsylvania
Daughter, age 17
Washington, Pennsylvania · implied b. ~1903 — 8 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| Father's Birthplace | Scotland |
| Mother's Birthplace | Scotland |
| Occupation | none |
| Can Read | Yes |
| Can Write | Yes |
| Speaks English | Yes |
| Mother Tongue | Scotch |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
1930
Washington, Pennsylvania
Daughter, age 27
Washington, Pennsylvania · implied b. ~1903 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 27 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| Father's Birthplace | Scotland |
| Mother's Birthplace | Scotland |
| Occupation | none |
| Can Read/Write | Yes |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
1940
Washington-County, Pennsylvania
Daughter, age 37
Washington-County, Pennsylvania · implied b. ~1903 — 4 household members
| Surname | McMahon |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 37 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | Monongahela City |
| 1935 Residence (County) | Washington |
| Occupation | Clerk |
| Industry | Retail Grocery Store |
| Class of Worker | PW |
| Hours Worked | 44 |
| Income (1939) | 588 |
| Highest Grade | No 8 |
| 1935 Residence | Same place |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
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 Mcmahon across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage. Identified parents: father James Mcmahon (~0.92 confidence) and mother Elizabeth Mcmahon (~0.92 confidence) and father James Mcmahon (~0.92 confidence). The pedigree spans 1 generation with 3 identified ancestors.
Show:
Gen 1
Parents
confidence ≈ 0.92
Father
James Mcmahon
b. ~1862
Source father
● Household
· direct · ~0.92
Mother
Elizabeth Mcmahon
b. ~1869
Source mother
● Household
· direct · ~0.92
Father
James Mcmahon
b. ~1869
Source father
● Household
· direct · ~0.92
This person
Anchor record
Mary Mcmahon
Daughter · 1940 · age 37 · b. ~1903 · Pennsylvania
★ You are viewing this record
Sibling
Thelma Mcmahon
Sibling · 1940 · age 32
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Grace Mcmahon
Sibling · 1940 · age 36
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 — Washington-County, Pennsylvania
Open full size
1940 US Federal Census — Washington-County, Pennsylvania
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-03624-00491)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Alphonsus Hill | 43 | Head | Labourer | Pennsylvania |
| 2 | Wilda Hill | 41 | Wife | — | Pennsylvania |
| 3 | Mabel Hill | 18 | Daughter | — | Pennsylvania |
| 4 | Dal C. Stevenson | 61 | Head | New Worker Boiler | Pennsylvania |
| 5 | Grace Stevenson | 56 | Wife | — | Pennsylvania |
| 6 | Gladys Stevenson | 18 | Daughter | — | Pennsylvania |
| 7 | Harold Stevenson | 16 | Son | — | Pennsylvania |
| 8 | Betty Stevenson | 13 | Daughter | — | Pennsylvania |
| 9 | Elizabeth Mcmahon | 71 | Head | — | Scotland |
| 10 | Mary Mcmahon THIS PERSON | 37 | Daughter | Clerk | Pennsylvania |
| 11 | Grace Mcmahon | 36 | Daughter | Machinist | Pennsylvania |
| 12 | Thelma Mcmahon | 32 | Daughter | Telephone Operator | Pennsylvania |
| 13 | Malcolm Mcmahon | 43 | Head | Fitter | Pennsylvania |
| 14 | Eva Mcmahon | 43 | Wife | — | Pennsylvania |
| 15 | Elizabeth Mcmahon | 23 | Daughter | Floor Lady | Pennsylvania |
| 16 | William Mcmahon | 18 | Son | — | Pennsylvania |
| 17 | James Mcmahon | 14 | Son | — | Pennsylvania |
| 18 | Malcolm Jr. Mcmahon | 10 | Son | — | Pennsylvania |
| 19 | John Demchak | 49 | Head | Labourer | Austria |
| 20 | Anna Demchak | 49 | Wife | — | Austria |
| 21 | John Jr. Demchak | 25 | Son | Labourer | Pennsylvania |
| 22 | Anna Demchak | 12 | Daughter | 26 | Pennsylvania |
| 23 | Pete Brown | 55 | Head | 604 | Pennsylvania |
| 24 | Charles Vitternick | 60 | Lodger | 52 | Austria |
| 25 | Eugene W. Albright | 40 | Head | Coal Miner | Pennsylvania |
| 26 | Goldie M. Albright | 35 | Wife | — | Pennsylvania |
| 27 | Catharine Albright | 15 | Daughter | — | Pennsylvania |
| 28 | Gene A. Albright | 8 | Son | — | Pennsylvania |
| 29 | Glenn A. Albright | 5 | Son | — | Pennsylvania |
| 30 | Charles Massey | 67 | Head | — | Pennsylvania |
| 31 | May L. Massey | 69 | Wife | — | Pennsylvania |
| 32 | Joseph Isger | 28 | Head | Fitter | Pennsylvania |
| 33 | Vileta Isger | 30 | Wife | — | Pennsylvania |
| 34 | Ronald Isger | 2 | Son | — | Pennsylvania |
| 35 | James H. Sutman | 59 | Head | 26 | Pennsylvania |
| 36 | James Ferraro | 59 | Head | 108 | Italy |
| 37 | Mary Ferraro | 54 | Wife | — | Italy |
| 38 | John Ferraro | 29 | Son | — | Pennsylvania |
| 39 | Elizabeth Ferraro | 27 | Daughter | Kitchen Helper | Pennsylvania |
| 40 | Patsy Ferraro | 22 | Son | 192 | Pennsylvania |
Pedigree Summary
Mary + 2 siblings
Gen 1 · 3 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)