William M. Dunn
Born: 13 June 1877, Dunn Co., Wisconsin
Source: Wisconsin Births 1820-1907.
In 1880 the family was living in Weston, Dunn, WI.
Chester C. Dunn, b. NY, 38, engineer.
Angie, wife, b. PA, 26.
W. Miner, b. WI, 3.
MAYBE your Angie
In 1885 Angie & C. M. were living in Mount Pleasant, Wabasha, Minnesota with the Livingston family.
Angie Dunn, b. abt. 1854, PA
C. M., male, 8, b. WI.
In 1900 Angie was living in Pinon, Montrose, CO.
Angie Dunn, b. June 1853, PA, had given birth to one child who was not alive in 1900, divorced.
However, Chester was living next door to her.
Chester Dunn, b. Jan 1842, NY, divorced.
I also found Sheila's Family Tree, trees.ancestry.com/tree/618745/person/15561010 which contains the Dunn family.
Chester C Dunn died 3 Jan 1926, mesa county, CO.
Anna "Angie" Matilda Heath b. June 1853, PA died 10 March 1902 but doesn't say where.
William Minor Dunn b. 13 June 1877 Weston, Dunn, WI died before 1900 CO. Buried: Montrose Cemetery, CO.
Source: Sheila's Family Tree.
Colorado doesn't publish death info and as far as I can tell, not even historical info. However, it's best to contact the Colorado Department of Public health & Environment, colorado.gov/cs/Satellite?c=Page&childpagename=CDP...
You can request a copy of a death certificate but they have restrictions which are listed on the above web site.
Colorado Archives does contain Montrose Co. Probate Cases 1883-1939. For additional info go to colorado.gov/dpa/doit/archives/hrd/index.htm. Successful Searching!