He was living in Kansas City, Missouri in the 1930 Census and was stated to be single. (Ref 1)

World War I Draft Registration Cards, 1917-1918 (Ref 2)
Name: Zanas Proffer
Address: Bernie
County: Stoddard
State: Missouri
Birthplace: Bloomfield, Stoddard County, Missouri
Birth Date: 3 Dec 1891
Race: American
FHL Roll Number: 1683932
DraftBoard: 0
Age: 25
Occupation: Farming
Nearest Relative: Not stated
Height/Build: medium/medium
Color of Eyes/Hair: grey/brown
Date: 5 Jun 1917

References
(1) 1930 Census, Missouri, Jackson County, Kansas City 2nd Ward Block 97, District 36, Sheet 2B, Household 48

(2) Ancestry.com, World War I Draft Registration Cards, 1917-1918 Record, Source Information: [database online]. Provo, UT: Ancestry.com, 2005. Original data: National Archives and Records Administration. World War I Selective Service System Draft Registration Cards, 1917-1918. M1509, 4,582 rolls. National Archives and Records Administration, Washington, D.C.