MD
Mary Dempsey — 1940 US Census Record
Linked across censuses1940 United States Federal Census · Lee-County, Illinois
Our Model Tree links this Mary Dempsey across the 1930 and 1940 US Censuses in Lee-County, Illinois (XGBoost, ~Confirmed) — first a daughter (b.~1920), then head of a 10-person household.
Age 20
b. ~1920
Female
Daughter
Born: Illinois
Single
1940 Census Record Details
| Census Year | 1940 |
| Location | Lee-County, Illinois |
| Surname | Dempsey |
| Given Name | Mary |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 20 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Marion township |
| 1935 Residence (County) | Lee |
| Additional Details | |
| Hours Worked | 5 |
| Income (1939) | 0 |
| Highest Grade | H 4 |
| 1935 Residence | Same place |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
| Township / Ward | Marion Township |
| Est. Birth Year | ~1920 |
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 Mary | Age | Birth yr |
|---|---|---|---|---|
| Mary Dempsey | Daughter | — | 20 | ~1920 |
| Arvella Dempsey | Daughter | — | 24 | ~1916 |
| Joan Dempsey | Daughter | — | 3 | ~1937 |
| William Dempsey | Son | — | 11 | ~1929 |
| Earl Dempsey | Son | — | 9 | ~1931 |
| Harry Dempsey | Head | — | 48 | ~1892 |
| Rita Dempsey | Daughter | — | 16 | ~1924 |
| Lenore Dempsey | Daughter | — | 22 | ~1918 |
| Joseph Dempsey | Son | — | 25 | ~1915 |
| Gertrude Dempsey | Spouse | — | 47 | ~1893 |
Census Appearances
1930
Lee, Illinois
Daughter, age 10
Lee, Illinois · implied b. ~1920 — 9 household members
●
Primary link
· ~Confirmed · 2 sources
XGBoost
Household
| Surname | Dempsey |
| Given Name | Mary |
| Relationship to Head | Daughter |
| Sex | F |
| Color / Race | White |
| Age | 10 |
| Marital Status | Single |
| Birthplace | Illinois |
| Father's Birthplace | Illinois |
| Mother's Birthplace | Illinois |
| Can Read/Write | Yes |
| Birth State | Illinois |
| Birth Country | United States |
| Birthplace (normalized) | illinois |
1940
Lee-County, Illinois
Daughter, age 20
Lee-County, Illinois · implied b. ~1920 — 10 household members
| Surname | Dempsey |
| Given Name | Mary |
| Relationship to Head | daughter |
| Sex | F |
| Color / Race | White |
| Age | 20 |
| Marital Status | Single |
| Birthplace | Illinois |
| 1935 Residence (City) | Marion township |
| 1935 Residence (County) | Lee |
| Hours Worked | 5 |
| Income (1939) | 0 |
| Highest Grade | H 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 Dempsey across 2 US Census years (1930 and 1940) in 2 locations, using XGBoost record linkage.
Show:
This person
Anchor record
Mary Dempsey
Daughter · 1940 · age 20 · b. ~1920 · Illinois
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Sibling
William Dempsey
Sibling · 1940 · age 11
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Joan Dempsey
Sibling · 1940 · age 3
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Earl Dempsey
Sibling · 1940 · age 9
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Arvella Dempsey
Sibling · 1940 · age 24
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Lenore Dempsey
Sibling · 1940 · age 22
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Joseph Dempsey
Sibling · 1940 · age 25
Source co-child of head (derived)
● Co-child · derived · ~0.88
Sibling
Rita Dempsey
Sibling · 1940 · age 16
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 — Lee-County, Illinois
Open full size
1940 US Federal Census — Lee-County, Illinois
Page Contents
40 people indexed on this census page (nara:1940:m-t0627-00836-00763)
| Line | Name | Age | Relation | Occupation | Birthplace |
|---|---|---|---|---|---|
| 1 | Regena Rogers | 20 | daughter | — | Illinois |
| 2 | William Fitzpatrick | 53 | head | Farmer | Illinois |
| 3 | Johanna Fitzpatrick | 48 | wife | Teacher | Illinois |
| 4 | William Fitzpatrick | 21 | son | — | Illinois |
| 5 | Patricia Fitzpatrick | 18 | daughter | — | Illinois |
| 6 | Bernard Fitzpatrick | 17 | son | — | Illinois |
| 7 | Harry Dempsey | 48 | head | Farmer | Illinois |
| 8 | Gertrude Dempsey | 47 | wife | — | Illinois |
| 9 | Joseph Dempsey | 25 | son | — | Illinois |
| 10 | Arvella Dempsey | 24 | daughter | — | Illinois |
| 11 | Lenore Dempsey | 22 | daughter | — | Illinois |
| 12 | Mary Dempsey THIS PERSON | 20 | daughter | — | Illinois |
| 13 | Rita Dempsey | 16 | daughter | — | Illinois |
| 14 | William Dempsey | 11 | son | — | Illinois |
| 15 | Earl Dempsey | 9 | son | — | Illinois |
| 16 | Joan Dempsey | 3 | daughter | — | Illinois |
| 17 | Robert Lowe | 25 | head | — | Illinois |
| 18 | Emma Lowe | 24 | wife | — | Illinois |
| 19 | Ilene Lowe | 0 | daughter | — | Illinois |
| 20 | Joseph Shulte | 53 | head | Farmer | Illinois |
| 21 | Anna Shulte | 43 | wife | — | Illinois |
| 22 | Kenneth Shulte | 18 | son | Farmer | Illinois |
| 23 | Everett Shulte | 13 | son | — | S. Dakota |
| 24 | Clement Morrissey | 36 | head | Farmer | Illinois |
| 25 | Margaret Morrissey | 31 | wife | — | Illinois |
| 26 | Regena Morrissey | 13 | daughter | — | Illinois |
| 27 | Thomas Morrissey | 7 | son | — | Illinois |
| 28 | Clarence Morrissey | 5 | son | — | Illinois |
| 29 | Thomas Morrissey | 77 | uncle | — | Illinois |
| 30 | William Donovan | 21 | laborer | Milk Truck | Illinois |
| 31 | Lena Blowers | 60 | nurse | — | Germany |
| 32 | Mike Mccoy | 57 | head | Farmer | Illinois |
| 33 | James Morrissey | 38 | head | Farmer | Illinois |
| 34 | Marie Morrissey | 36 | wife | — | Illinois |
| 35 | Mary M Morrissey | 13 | daughter | — | Illinois |
| 36 | Elinore Morrissey | 10 | daughter | — | Illinois |
| 37 | James Morrissey | 9 | son | — | Illinois |
| 38 | Charles Morrissey | 7 | son | — | Illinois |
| 39 | Joseph Morrissey | 5 | son | — | Illinois |
| 40 | Steven Morrissey | 1 | 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)