The reason you have had trouble locating John Roth's death date in Montana is because he did not die in Montana...he died in Massachusetts in 1943.
Marriage certificates
9Dec1887 Miles City
John Roth
age 30
Single
Born East Shodick, Rensselaer Co, New York
Parents Joseph Roth & Mary Hummel
Spouse. Mattie J Patterson
age 30
Born Alabama
Parents RA Patterson & AA Bass
21Oct1903 Pittsfield, Berkshire Co, Massachusetts
John Roth
Age 43
Born East Shodack, New York
Parents Joseph Roth & Mary A Hammel
First marriage
Paper hanger
Spouse. Margaret Keegan
Age 26
Born England
Parents Daniel Keegan & Joanna Kennedy
First marriage
Housework
1920 Pittsfield, Massachusetts
John Roth (indexed Roch)59 electric worker, born NY, parents Germany
Margaret 39 England
Edgar 15
Edna 13
1930 census Pittsfield same but without Edgar
1940 census Pittsfield
John & Margaret, owned home on Cole Avenue, John 6th grade education
John Roth death 3 Dec 1943 Pittsfield, Mass
New York interment index
Buried Woodlawn, Rensselaer, NY
Schodack
B1860. Burial1943
Wife Margaret Keegsn
Edgar J death 2001, Georgia
Edna M born 1906, married Munger
[This message has been edited by Cindy Stalcup (2/12/2014)]