ML
Mary Leahy — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Sangamon-County, Illinois
Our Model Tree links this Mary Leahy across the 1930 and 1940 US Censuses in Sangamon-County, Illinois (XGBoost, ~Confirmed) — first a daughter (b.~1930), then head of a 4-person household.
Age 10
b. ~1930
Female
Daughter
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Sangamon-County, Illinois |
| Surname | Leahy |
| Given Name | Mary Ann |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Pleasant Plains |
| 1935 Residence (County) | Sangamon |
| Additional Details | |
| Highest Grade | No 4 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Pleasant Plains |
| Est. Birth Year | ~1930 |
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 |
|---|---|---|---|---|
| Jimmie Leahy | Son | — | 6 | ~1934 |
| Helen Leahy | Spouse | — | 39 | ~1901 |
| Leo Leahy | Head | — | 41 | ~1899 |
| Mary Leahy | Daughter | — | 10 | ~1930 |
Census Appearances
1930
Sangamon, Illinois
Daughter, age
Sangamon, Illinois · implied b. ~1930 — 4 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Leahy |
| Given Name | Mary Ann |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 0 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Sangamon-County, Illinois
Daughter, age 10
Sangamon-County, Illinois · implied b. ~1930 — 4 household members
| Surname | Leahy |
| Given Name | Mary Ann |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Pleasant Plains |
| 1935 Residence (County) | Sangamon |
| Highest Grade | No 4 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
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 Leahy across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
Mary Leahy
Daughter · 1940 · age 10 · b. ~1930 · Illinois
★ You are viewing this record
Sibling
Jimmie Leahy
Sibling · 1940 · age 6
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 — Sangamon-County, Illinois
Open full size
1940 US Federal Census — Sangamon-County, Illinois
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00887-00044)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 41 | Bessie Haynes | 45 | Head | Housewife | Illinois |
| 42 | Byron Haynes | 19 | Son | Help On | Illinois |
| 43 | J. Orville Pierson | 38 | Head | Farm Hand | Missouri |
| 44 | Alma Pierson | 41 | Wife | — | Missouri |
| 45 | Lois Pierson | 20 | Daughter | House Work | Missouri |
| 46 | Laura Mae Pierson | 15 | Daughter | — | Illinois |
| 47 | Ruth Pierson | 14 | Daughter | — | Illinois |
| 48 | Harvey Blakeman | 51 | Head | Farm Hand | Kentucky |
| 49 | Ruth Blakeman | 44 | Wife | — | Kentucky |
| 50 | Thales Blakeman | 16 | Son | — | Illinois |
| 51 | Glenn Blakeman | 13 | Son | — | Illinois |
| 52 | James E. Blakeman | 7 | Son | — | Illinois |
| 53 | W. P. Leahy | 65 | Head | Farm Owner | Illinois |
| 54 | Emma Leahy | 62 | Wife | — | Illinois |
| 55 | Rufus Spann | 21 | Head | Farm Hand | Kentucky |
| 56 | Bertha Mae Spann | 19 | Wife | — | Illinois |
| 57 | L. Marie Spann | 1 | Daughter | — | Illinois |
| 58 | Leroy Spann | 16 | Brother | — | Kentucky |
| 59 | Jesse Alexander | 34 | Head | Farm Hand | Kentucky |
| 60 | Eva L. Alexander | 34 | Wife | — | Kentucky |
| 61 | Mary Jane Alexander | 11 | Daughter | — | Illinois |
| 62 | Mollie Cogdall | 47 | Head | Housewife | Illinois |
| 63 | Mae Wallbaum | 41 | Lodger | Farm Owner | Illinois |
| 64 | Leo Leahy | 41 | Head | Farmer | Illinois |
| 65 | Helen Leahy | 39 | Wife | — | Illinois |
| 66 | Mary Ann Leahy THIS PERSON | 10 | Daughter | — | Illinois |
| 67 | Jimmie Lee Leahy | 6 | Son | — | Illinois |
| 68 | Charles Bachmann | 70 | Head | Farmer | Illinois |
| 69 | Carrie Bachmann | 66 | Wife | — | Illinois |
| 70 | Minnie Klotz | 54 | Sister in Law | — | Illinois |
| 71 | Fred Wells | 26 | Head | Farm Hand | Illinois |
| 72 | Ruby Wells | 26 | Wife | — | Kentucky |
| 73 | Claude Williamson | 37 | Head | Farmer Renter | Illinois |
| 74 | Carrie L. Williamson | 28 | Wife | — | Illinois |
| 75 | Leda O. Williamson | 11 | Daughter | — | Illinois |
| 76 | Ralph Lee Williamson | 9 | Son | — | Illinois |
| 77 | Elbert E. Williamson | 7 | Son | — | Illinois |
| 78 | Thomas Grant | 26 | Head | Farm Hand | Kentucky |
| 79 | Esther V. Grant | 28 | Wife | — | Illinois |
| 80 | T. Kenneth Grant | 2 | Son | — | Illinois |
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)