JM
James Mcmahon — 1940 US Census Record
Model Tree available1940 United States Federal Census · Washington-County, Pennsylvania
Our Model Tree links this James Mcmahon across the 1920, 1930 and 1940 US Censuses in Washington-County, Pennsylvania (XGBoost, ~Confirmed), with identified parents James & James — first a head (b.~1901), then head of a 4-person household.
Age 39
b. ~1901
Male
Head
Born: Scotland
Married
1940 Census Record Details
| Census Year | 1940 |
| Location | Washington-County, Pennsylvania |
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Head |
| Sex | M |
| Color / Race | White |
| Age | 39 |
| Marital Status | Married |
| Birthplace | Scotland |
| 1935 Residence (City) | MONONGAHELA |
| 1935 Residence (County) | WASHINGTON |
| Naturalization Status | Naturalized |
| Additional Details | |
| Occupation | Postal Clerk |
| Industry | US Post Office |
| Class of Worker | GW |
| Hours Worked | 40 |
| Income (1939) | 2100 |
| Highest Grade | No 8 |
| 1935 Residence | Same place |
| Birth Country | Scotland |
| Birthplace (normalized) | scotland |
| Occupation | Postal Clerk |
| Township / Ward | Monongahela |
| Est. Birth Year | ~1901 |
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 James | Age | Birth yr |
|---|---|---|---|---|
| Mary Mcmahon | Daughter | — | 3 | ~1937 |
| Doris Mcmahon | Daughter | — | 11 | ~1929 |
| James Mcmahon | Head | — | 39 | ~1901 |
| Mary Mcmahon | Spouse | — | 33 | ~1907 |
Census Appearances
1920
Washington, Pennsylvania
Son, age 18
Washington, Pennsylvania · implied b. ~1902 — 8 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 18 |
| Marital Status | Single |
| Birthplace | Scotland |
| Naturalization Status | Naturalized |
| Father's Birthplace | Scotland |
| Mother's Birthplace | Scotland |
| Occupation | Telephone Boy |
| Industry | Railroad |
| Class of Worker | W |
| Can Read | No |
| Can Write | No |
| Speaks English | Yes |
| Mother Tongue | Scotch |
| Birth Country | Scotland |
| Birthplace (normalized) | scotland |
1930
Washington, Pennsylvania
Son, age 29
Washington, Pennsylvania · implied b. ~1901 — 6 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 29 |
| Marital Status | Single |
| Birthplace | Scotland |
| Naturalization Status | Naturalized |
| Year of Immigration | 1902 |
| Father's Birthplace | Scotland |
| Mother's Birthplace | Scotland |
| Occupation | Mail carrier |
| Industry | Govt. P.O. |
| Class of Worker | W |
| Can Read/Write | Yes |
| Mother Tongue | English |
| Veteran | No |
| Birth Country | Scotland |
| Birthplace (normalized) | scotland |
1940
Washington-County, Pennsylvania
Head, age 39
Washington-County, Pennsylvania · implied b. ~1901 — 4 household members
| Surname | McMahon |
| Given Name | James |
| Relationship to Head | Head |
| Sex | M |
| Color / Race | White |
| Age | 39 |
| Marital Status | Married |
| Birthplace | Scotland |
| 1935 Residence (City) | MONONGAHELA |
| 1935 Residence (County) | WASHINGTON |
| Naturalization Status | Naturalized |
| Occupation | Postal Clerk |
| Industry | US Post Office |
| Class of Worker | GW |
| Hours Worked | 40 |
| Income (1939) | 2100 |
| Highest Grade | No 8 |
| 1935 Residence | Same place |
| Birth Country | Scotland |
| Birthplace (normalized) | scotland |
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 James 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 father James Mcmahon (~0.92 confidence) and mother Elizabeth 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
Father
James Mcmahon
b. ~1869
Source father
● Household
· direct · ~0.92
Mother
Elizabeth Mcmahon
b. ~1870
Source mother
● Household
· direct · ~0.92
This person
Anchor record
James Mcmahon
Head · 1940 · age 39 · b. ~1901 · Pennsylvania
★ You are viewing this record
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-t0627-03624-00500)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | William Murray | 64 | Head | — | Ohio |
| 42 | Ellen Murray | 65 | Wife | — | Wales |
| 43 | William M Murray | 40 | Son | Clerk | Pennsylvania |
| 44 | Ann M Murray | 35 | In law | — | Pennsylvania |
| 45 | William Murray | 11 | Grandson | — | Pennsylvania |
| 46 | Eileen Murray | 4 | Granddaughter | — | Pennsylvania |
| 47 | William H B Godfrey | 52 | Head | Laborer | Pennsylvania |
| 48 | James B B Godfrey | 51 | Head | Laborer | Pennsylvania |
| 49 | Raffaele De Santis | 57 | Head | Stone Mason | Italy |
| 50 | Catherine De Santis | 51 | Wife | — | Italy |
| 51 | Mary De Santis | 28 | Daughter | Bookkeeper | Pennsylvania |
| 52 | Samuel De Santis | 26 | Son | Elec Welder | Pennsylvania |
| 53 | Michael De Santis | 24 | Son | Elec Welder | Pennsylvania |
| 54 | Angit De Santis | 19 | Daughter | Clerk | Pennsylvania |
| 55 | Julia A Barclay | 65 | Head | Practical Nurse | Pennsylvania |
| 56 | Wade B Barclay | 35 | Son | Proprietor | Pennsylvania |
| 57 | Mary M Barclay | 36 | In law | — | Pennsylvania |
| 58 | James F Barclay | 13 | Grandson | — | Pennsylvania |
| 59 | Frank J Jr Ellsworth | 20 | Head | Truck Driver | Pennsylvania |
| 60 | Wilma Ellsworth | 24 | Wife | — | Pennsylvania |
| 61 | Albert H Smith | 44 | Head | Pipe Line Repairman | Pennsylvania |
| 62 | Frances Smith | 43 | Wife | — | Pennsylvania |
| 63 | Albert E Smith | 21 | Son | Laborer | Pennsylvania |
| 64 | George W Smith | 18 | Son | — | Pennsylvania |
| 65 | Doris A Smith | 13 | Daughter | — | Pennsylvania |
| 66 | J Earl Smith | 11 | Son | — | Pennsylvania |
| 67 | Raymond D Smith | 7 | Son | — | Pennsylvania |
| 68 | Nancy Lou Smith | 3 | Daughter | — | Pennsylvania |
| 69 | Martha J Smith | 20 | Daughter | — | Pennsylvania |
| 70 | Peter Jr Matznger | 32 | Boarder | Laborer | Pennsylvania |
| 71 | Wasily Stroyer | 53 | Head | Clergyman | Czechoslovakia |
| 72 | Anna Stroyer | 49 | Wife | — | Czechoslovakia |
| 73 | William B Stroyer | 13 | Son | — | Pennsylvania |
| 74 | James N Felice | 37 | Head | Electrician | Pennsylvania |
| 75 | Irene R Felice | 35 | Wife | — | Pennsylvania |
| 76 | James N Jr Felice | 1 | Son | — | Pennsylvania |
| 77 | James Mcmahon THIS PERSON | 39 | Head | Postal Clerk | Scotland |
| 78 | Mary E Mcmahon | 33 | Wife | — | Pennsylvania |
| 79 | Doris J Mcmahon | 11 | Daughter | — | Pennsylvania |
| 80 | Mary J Mcmahon | 3 | Daughter | — | Pennsylvania |
Pedigree Summary
James
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)