Hello, Sigurd,
Is this Walter Otto RUSCH? My search finds a document that may be for him. If this truly is your relative, the different given name may lead to other records in Chicago....
document at Ancestry.com:
U.S.A. registration for military draft, World War I
document date of: 12 Sep 1918
place of Chicago Local [draft] Board No. 41:
Chicago, Illinois (South Wood Street, #546-548)
registration card for: Otto Frank RUSCH
his home address: Chicago, West Congress Street, #1926
his date of birth: 10 Feb 1886
his place of birth: Germany
his occupation: machinist [The employer name is not clearly readable.]
his work address: Chicago (Rockwell Street & 19th Street)
his nearest relative: Emil RUSCH
home address of Emil: Chicago, West Congress Street, #1926
signature: Otto RUSCH
personal description of Otto: medium height, medium build, brown eyes, black hair
With best wishes,
Gordon Seyffert
Kansas City, Missouri, U.S.A.