Father: John (Joannes) Jansen b. 1837 in Oosterholt, Gelderland, Netherlands d. 1896 m. 9 Aug 1862 in Saint John Nepomucene, Little Chute, Wisconsin
Mother: Maria Margaret St. Louis b. 9 Sep 1842 in Little Chute, Outagamie, Wisconsin d. 12 Jan 1910 in Marinette, Marinette, Wisconsin.

Extract from the 1880 Census:
Name: Isadore Jansen
Age: 4
Estimated birth year: 1876
Birthplace: Wisconsin
Race: white
Sex: male
Relationship to head-of-household: son
Parents: John and Margaret Jansen, ages 41 and 37
Home in 1880: Milltown, Shawano, Wisconsin
Marital status: single
Father's birthplace: Holland
Mother's birthplace: Wisconsin
Father's occupation: farmer and merchant
Occupation: none
Siblings living at home: Amelia (age 16), Mary L (13), Moses (2), and Edith (8/12)
Census place: Milltown, Shawano, Wisconsin; Roll: T9_1447; Family History Film: 1255447; Page: 376.4000; Enumeration District: 155
Date: 15 Jun 1880

First extract from the 1905 Wisconsin State Census:
Name: Isador Jansen
Age: 29
Estimated birth year: 1876
Birth location: Wisconsin
Race: white
Gender: male
Relation to head of house: head
Residence county: Langlade
Residence state: Wisconsin
Locality: Antigo
Marital status: married
Father's birth location: Canada [sic]
Mother's birth location: Canada [sic]
Farm or home: home
Owned or rented: owned
Mortgage: no
Occupation: store clerk
Months employed: 12
Census date: 1 Jun 1905

Extract from the 1911 Census of Canada:
Name: Isadore Jacob Jansen
Birth date: Feb 1875 [sic]
Birthplace: United States
Gender: male
Relation to head-of-house: head
Home in 1911: Calgary, Calgary, Alberta
Address: 2346 15th Street West
Marital status: married
Year of immigration: 1910
Origin: Dutch
Able to read: yes
Able to write: yes
Religion: Methodist
Occupation: storekeeper - grocery
Employer: working on own account
Weeks employed: 52
Hours worked per week: 60
Total earnings in 1910: $1500
Life insurance held: $3000
Province: Alberta
District: Calgary
District number: 1
Sub-district: Calgary
Sub-district number: 47
Census place: Calgary, Calgary, Alberta. Page 4, Family No: 41

Extract from World War I Draft Registration Cards, 1917-1918:
Name: Isadore J Jansen
City: Rhinelander
County: Oneida
State: Wisconsin
Birth date: 11 Feb 1876 [source for date of birth]
Race: white
Roll: 1674879
Draft board: 0
Address: Pelican Lake, Oneida, Wisconsin
Occupation: merchant
Where employed: Pelican Lake, Oneida, Wisconsin
Nearest relative: Hanna Jansen
Address: Pelican Lake, Oneida, Wisconsin
Age: 42
Height: medium
Build: medium
Eyes: blue
Hair: brown
Date: 12 Sep 1918

Extract from the 1920 Census:
Name: Isadore J Jansen
Age: 44
Estimated birth year: 1876
Birthplace: Wisconsin
Race: white
Sex: male
Relationship to head of house: head
Home in 1920: Schoepke, Oneida, Wisconsin
Marital status: married
Able to speak English: yes
Able to read and write: yes
Father's birthplace: Holland
Father's native tongue: French
Mother's birthplace: France
Mother's native tongue: French
Home owned or rented: owned; no mortgage
Occupation: merchant
Type of industry: general store
Salary or wage worker: working on own account
Census place: Schoepke, Oneida, Wisconsin; Roll: T625_2008; Page: 5B; Enumeration District: 129; Image: 50
Date: 5 Mar 1920

Extract from the 1930 Census:
Name: Isadore J Jansen
Age: 55
Estimated birth year: 1875
Birthplace: Wisconsin
Race: white
Sex: male
Relation to head-of-house: head
Home in 1930: Schoepke, Oneida, Wisconsin
Marital status: married
Age at first marriage: 22
Education: able to speak English
Education: able to read and write
Father's birthplace: Holland
Mother's birthplace: Wisconsin
Military service: no
Rent/home value: owns home; value $3500
Owned a radio: yes
Occupation: merchant
Industry: general store
Salary or wage worker: working on own account
Census place: Schoepke, Oneida, Wisconsin; Roll: 2602; Page: 1A; Enumeration District: 19; Image: 492.0
Date: 2 Apr 1930

Extract from the 1940 Census:
Name: J Isador Jansen
Age: 64
Estimated birth year: 1876
Birthplace: Wisconsin
Race: white
Sex: male
Relation to head-of-house: head
Home in 1940: Schoepke, Oneida, Wisconsin
Marital status: married
Highest grade of school completed: high school 4 years
Living on farm: no
Home owned or rented: owned
Value of home: $1200
Place of residence in 1935: same house
Occupation: retired merchant
Has other income of more than $50: yes
Census place: Schoepke, Oneida, Wisconsin; Roll: T627_4507; Page: 2B; Enumeration District: 43-24
Date: 6 Apr 1940

Extract from the 1950 Census:
Name: Isador J Jansen
Age: 75
Estimated birth year: 1875
Birthplace: Wisconsin
Race: white
Sex: male
Relation to head-of-house: head
Home in 1950: Schoepke, Oneida, Wisconsin
Address: Highway 45 - 47
Marital status: married
Living on farm: no
Occupation: none
Class of worker: unable to work
Census place: Schoepke, Oneida, Wisconsin
Date: 8 May 1950

Obituary from the "Daily Journal" of Antigo, Wisconsin dated 21 Nov 1961:
Isador Jansen,
85, Pelican Lake,
Dies on Monday
Isador Jansen, former resort owner and operator of the Wildwood grocery store at Pelican Lake died Monday at Milwaukee where he was visiting. He made his home at Pelican Lake.
Mr. Jansen came from Little Chute to Phlox before 1900. On Aug. 19, 1915, he was married at Wisconsin Rapids to Hannah Havverson.
Two children survive. They are Mrs. Gladyce Porten DeLoye and Kenneth Jansen, both of Milwaukee. Also surviving are two grandchildren, five great-grandchildren and a sister, Mrs. Frank Whelan of Lanark Village, Fla.
His wife died Dec. 11 of last year. He was also predeceased by sisters and brothers including Mose Jansen of Antigo.
Funeral services will be held at 10 a.m. Friday at the Soman and Rhodes funeral chapels with the Rev. Cyril Kabat officiating. Burial will be at Wittenberg.
Friends may call at the funeral chapels from 8 p.m. Thursday.

He married (1) Ethel Gertrude Rice 2 Apr 1902 in Antigo, Langlade, Wisconsin.
He married (2) Hannah H Halvorson 19 Aug 1915 in Wisconsin Rapids, Wood, Wisconsin.