The original "Chicago Tribune" article about the 'Mystery' of the Arlington Cemetery (in Elmhurst, Ill.) SAW veteran burials was published in May, 2002.

Later that year, in October, 2002, a Tribune article gave the update and explanation.

The Elmhurst Museum Curator (at the time), Nancy Wilson, answered her own question, as reported in the October article.
She did research, in September, 2002, at the Chicago Historical Society and discovered the connection of the Veteran Graves to the United Spanish War Veterans 'Post' (William McKinley - Camp #6) in Chicago.

Not much to tell the current curator, if she/he has access to predecessor's work.
However, the names on the tombstones would allow matching to lists of known SAW period veterans.

It is understandable that a lot of SAW veterans would move to jobs & careers in a booming metropolis like Chicago.
(Fraternal groups and Veteran Organizations, like the GAR, USWV, and VFW were huge from the 1890's to mid 1900's).

Interesting thread 'King Carp'! Thanks 'Culpeper' and 'Knute' for the links to the Tribune articles.