From Political Graveyard:
Campbell, Robert A. (born c.1870) — of Ann Arbor, Washtenaw County, Mich. Born in Canada, about 1870. Republican. Treasurer, University of Michigan; mayor of Ann Arbor, Mich., 1925-27, 1933-37; defeated, 1927. Scottish ancestry. Burial location unknown.
Obituary in the New York Times, 7 Nov 1947: p. 23.