JM
James Mcmahon — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Chester-County, Pennsylvania
Our Model Tree links this James Mcmahon across the 1930 and 1940 US Censuses in Chester-County, Pennsylvania (XGBoost, ~Confirmed) — first a son (b.~1912), then head of a 10-person household.
Age 28
b. ~1912
Male
Son
Born: Pennsylvania
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Chester-County, Pennsylvania |
| Surname | McMahon |
| Given Name | James R. Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 28 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | London Grove Twp. |
| 1935 Residence (County) | Chester |
| Additional Details | |
| Occupation | Garage Mechanic |
| Industry | Public Garage |
| Class of Worker | PW |
| Hours Worked | 49 |
| Income (1939) | 1300 |
| Highest Grade | Hs 4 |
| 1935 Residence | Same place |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
| Occupation | Garage Mechanic |
| Township / Ward | London Grove Twp |
| Est. Birth Year | ~1912 |
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.
10 people recorded at the same address in the 1940 census.
| Name | Relation to head | Relative to James | Age | Birth yr |
|---|---|---|---|---|
| Mayra Mcmahon | Daughter | — | 34 | ~1906 |
| Abigail Mcmahon | Daughter | — | 16 | ~1924 |
| James Mcmahon | Head | — | 69 | ~1871 |
| Carl Mcmahon | Son | — | 18 | ~1922 |
| Francis Mcmahon | Son | — | 22 | ~1918 |
| Paul Mcmahon | Son | — | 20 | ~1920 |
| James Mcmahon | Son | — | 28 | ~1912 |
| D Mcmahon | Son | — | 32 | ~1908 |
| Joseph Mcmahon | Son | — | 24 | ~1916 |
| Katie Mcmahon | Spouse | — | 64 | ~1876 |
Census Appearances
1930
Chester, Pennsylvania
Son, age 17
Chester, Pennsylvania · implied b. ~1913 — 11 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | McMahon |
| Given Name | James R. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 17 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| Father's Birthplace | Pennsylvania |
| Mother's Birthplace | Pennsylvania |
| Occupation | Laborer |
| Industry | At home |
| Class of Worker | W |
| Can Read/Write | Yes |
| Birth State | Pennsylvania |
| Birth Country | United States |
| Birthplace (normalized) | pennsylvania |
1940
Chester-County, Pennsylvania
Son, age 28
Chester-County, Pennsylvania · implied b. ~1912 — 10 household members
| Surname | McMahon |
| Given Name | James R. Jr. |
| Relationship to Head | Son |
| Sex | M |
| Color / Race | White |
| Age | 28 |
| Marital Status | Single |
| Birthplace | Pennsylvania |
| 1935 Residence (City) | London Grove Twp. |
| 1935 Residence (County) | Chester |
| Occupation | Garage Mechanic |
| Industry | Public Garage |
| Class of Worker | PW |
| Hours Worked | 49 |
| Income (1939) | 1300 |
| Highest Grade | Hs 4 |
| 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 James Mcmahon across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
James Mcmahon
Son · 1940 · age 28 · b. ~1912 · Pennsylvania
★ You are viewing this record
Sibling
Abigail Mcmahon
Sibling · 1940 · age 16
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Paul Mcmahon
Sibling · 1940 · age 20
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Carl Mcmahon
Sibling · 1940 · age 18
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
D Mcmahon
Sibling · 1940 · age 32
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Francis Mcmahon
Sibling · 1940 · age 22
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Joseph Mcmahon
Sibling · 1940 · age 24
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Mayra Mcmahon
Sibling · 1940 · age 34
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 — Chester-County, Pennsylvania
Open full size
1940 US Federal Census — Chester-County, Pennsylvania
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-03465-00513)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | James W. Taylor | 10 | Head | — | Delaware |
| 42 | Howard W. Taylor | 6 | Son | — | Delaware |
| 43 | Mary E. Taylor | 0 | Granddaughter | — | Pennsylvania |
| 44 | Herman R. Darnel | 51 | Head | Sawyer | Pennsylvania |
| 45 | Dora B. Darnel | 50 | Wife | — | Maryland |
| 46 | William M. Darnel | 25 | Son | Gas Station Att | Delaware |
| 47 | Edward R. Darnel | 22 | Son | Farm Laborer | Delaware |
| 48 | Isabel C. Darnel | 22 | Daughter | General Clerk | Delaware |
| 49 | Martin V. Darnel | 18 | Son | Truck Driver | Pennsylvania |
| 50 | Norman Jordan | 39 | Head | Farm Laborer | Pennsylvania |
| 51 | Sara Jordan | 36 | Wife | Paver | New Jersey |
| 52 | Kenneth Jordan | 15 | Son | — | New Jersey |
| 53 | George R. Davis | 63 | Head | Farm Owner | Pennsylvania |
| 54 | Ruth E. Davis | 53 | Wife | — | Pennsylvania |
| 55 | George R. Jr. Davis | 21 | Son | Farm Operator | Pennsylvania |
| 56 | Anna B. Davis | 19 | Daughter | Waitress | Pennsylvania |
| 57 | Mary E. Myers | 86 | Mother-in-law | — | Pennsylvania |
| 58 | Evan Story | 70 | Head | — | Pennsylvania |
| 59 | Herman C. Story | 42 | Son | Welder | Pennsylvania |
| 60 | Grace Story | 40 | Daughter-in-law | — | Pennsylvania |
| 61 | Clarence Porter | 51 | Head | Farm Operator | Pennsylvania |
| 62 | Rhoda Porter | 50 | Wife | — | Pennsylvania |
| 63 | Bayard Porter | 17 | Son | — | Pennsylvania |
| 64 | Raymond Porter | 14 | Son | — | Pennsylvania |
| 65 | Robert Porter | 8 | Son | — | Pennsylvania |
| 66 | Bayard Shivery | 86 | Father-in-law | — | Pennsylvania |
| 67 | James R. Mcmahon | 69 | Head | Farm Operator | Pennsylvania |
| 68 | Katie Mcmahon | 64 | Wife | — | Pennsylvania |
| 69 | Mayra A. Mcmahon | 34 | Daughter | Typewriter | Pennsylvania |
| 70 | D. Walter Mcmahon | 32 | Son | Garage Mechanic | Pennsylvania |
| 71 | James R. Jr. Mcmahon THIS PERSON | 28 | Son | Garage Mechanic | Pennsylvania |
| 72 | Francis Mcmahon | 22 | Son | Helper | Pennsylvania |
| 73 | Paul Mcmahon | 20 | Son | Farm Laborer | Pennsylvania |
| 74 | Carl Mcmahon | 18 | Son | Farm Laborer | Pennsylvania |
| 75 | Abigail Mcmahon | 16 | Daughter | — | Pennsylvania |
| 76 | Joseph F. Mcmahon | 24 | Son | Farm Laborer | Pennsylvania |
| 77 | Phoebe Mattson | 47 | Head | Servant | Pennsylvania |
| 78 | Charles Mattson | 25 | Son | Farm Laborer | Pennsylvania |
| 79 | George Mattson | 24 | Son | Farm Laborer | Pennsylvania |
| 80 | Harry Mattson | 22 | Son | Farm Laborer | Pennsylvania |
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)