Mary Mcmahon — 1940 US Census Record

Linked across censuses

1940 United States Federal Census · Cook-County, Illinois

Our Model Tree links this Mary Mcmahon across the 1920, 1930 and 1940 US Censuses in Cook-County, Illinois (XGBoost, ~Confirmed) — first a head (b.~1874), then head of a 3-person household.

Age 66 b. ~1874 Female Head Born: Illinois Widowed

1940 Census Record Details

Census Year	1940
Location	Cook-County, Illinois
Surname	McMahon
Given Name	Mary
Relationship to Head	head
Sex	F
Color / Race	White
Age	66
Marital Status	Widowed
Birthplace	Illinois
1935 Residence (City)	Chicago City
1935 Residence (County)	Cook
Additional Details
Highest Grade	8
1935 Residence	Same place
Birth State	Illinois
Birth Country	United States
Birthplace (normalized)	illinois
Township / Ward	Chicago City
Est. Birth Year	~1874

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.

3 people recorded at the same address in the 1940 census.

Name	Relation to head	Relative to Mary	Age	Birth yr
Lillian Coulson	Daughter	—	43	~1897
Mary Mcmahon	Head	—	66	~1874
John Mangan	Other	—	64	~1876

Census Appearances

1920

Cook, Illinois

Spouse, age 46

Cook, Illinois · implied b. ~1874 — 5 household members

● Primary link · ~Confirmed · 2 sources

XGBoost Household

Surname	McMahon
Given Name	Mary J
Relationship to Head	Wife
Sex	F
Color / Race	White
Age	46
Marital Status	Married
Birthplace	Illinois
Father's Birthplace	Ireland
Mother's Birthplace	Ireland
Occupation	none
Can Read	Yes
Can Write	Yes
Speaks English	Yes
Mother Tongue	English
Birth State	Illinois
Birth Country	United States
Birthplace (normalized)	illinois

1930

Cook, Illinois

Spouse, age 55

Cook, Illinois · implied b. ~1875 — 3 household members

● Primary link · ~Confirmed · 2 sources

XGBoost Household

Surname	McMahon
Given Name	Mary
Relationship to Head	Wife
Sex	F
Color / Race	White
Age	55
Marital Status	Married
Birthplace	Illinois
Age at First Marriage	35
Father's Birthplace	Ireland
Mother's Birthplace	England
Can Read/Write	Yes
Birth State	Illinois
Birth Country	United States
Birthplace (normalized)	illinois

1940

Cook-County, Illinois

Head, age 66

Cook-County, Illinois · implied b. ~1874 — 3 household members

Surname	McMahon
Given Name	Mary
Relationship to Head	head
Sex	F
Color / Race	White
Age	66
Marital Status	Widowed
Birthplace	Illinois
1935 Residence (City)	Chicago City
1935 Residence (County)	Cook
Highest Grade	8
1935 Residence	Same place
Birth State	Illinois
Birth Country	United States
Birthplace (normalized)	illinois

Model Tree

Linked across censuses

Our Model Tree links Mary Mcmahon across 3 US Census years (1920, 1930 and 1940) in 2 locations, using XGBoost record linkage.

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This person

Anchor record

Mary Mcmahon

Head · 1940 · age 66 · b. ~1874 · Illinois

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Confirmed / household (~0.90+) Probable / derived (~0.65–0.89) Candidate (<0.65, unverified)

Original Census Page

1940 US Federal Census — Cook-County, Illinois Open full size

Page Contents

40 people indexed on this census page (nara:1940:m-t0627-00932-00870)

Line	Name	Age	Relation	Occupation	Birthplace
1	Anna Francis	11	daughter	—	Illinois
2	Mary Ann Francis	12	daughter	—	Illinois
3	Robert Rees	50	head	Conductor	Illinois
4	Emily D Rees	46	wife	—	Illinois
5	Robert Rees	24	son	Ribbon Seller	Illinois
6	Emily E Rees	22	daughter	Stenographer	Illinois
7	Amy Rees	20	daughter	Clerk	Illinois
8	Elizabeth Rees	12	daughter	—	Illinois
9	Catherine Hardy	75	head	—	Illinois
10	Eugene Reilly	57	head	Motorman	Wisconsin
11	Clara E Reilly	52	wife	—	Illinois
12	Mary Jane Reilly	25	daughter	—	Illinois
13	James Reilly	22	son	Butcher	Illinois
14	Robert Reilly	20	son	Salesman	Illinois
15	William Reilly	15	son	—	Illinois
16	Steven Cornelius	45	head	Bartender	Greece
17	Mary Cornelius	36	wife	Waitress	Greece
18	Mabel Cornelius	17	daughter	—	Illinois
19	James Cornelius	12	son	—	Illinois
20	Katherine Roberts	52	head	Bookkeeper	Illinois
21	Joan Roberts	21	daughter	—	Illinois
22	Julia Farrell	80	mother	—	Wisconsin
23	Henry Charbonnier	57	head	Laborer	Illinois
24	Clara Charbonnier	50	wife	—	Illinois
25	John Lambrakis	44	lodger	Chef	Greece
26	Alex Makris	45	lodger	Bartender	Greece
27	Willis Gregory	48	head	Mail Clerk	New York
28	Inez Gregory	39	wife	—	Oklahoma
29	Mary Mcmahon THIS PERSON	66	head	—	Illinois
30	Lillian Coulson	43	daughter	Operator	Illinois
31	John Mangan	64	father	—	Ireland
32	Eliz. G Mckenna	88	head	—	New York
33	Andrew Christian	60	son-in-law	Salesman	Indiana
34	Esther Christian	57	daughter	—	Indiana
35	Emily Wilson	81	lodger	—	New York
36	Peter Zihit	42	head	Proprietor	Greece
37	Helen Zihit	40	wife	—	Greece
38	Thomas Zihit	14	son	Proprietor	Illinois
39	Louise Duerfer	46	head	Teacher	Ohio
40	Leonard Albers	38	head	Furrier	Illinois

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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)

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