Special election to fill vacancy caused by the death of Woodbridge N. Ferris. The winner would complete the unexpired term ending March 4, 1929. Arthur H. Vandenberg was initially appointed and ran in (and won) both the special and regular elections.
Source for Popular Vote data: Michigan Secretary of State. Michigan Official Directory and Legislative Manual 1929-1930, Michigan Secretary of State (https://babel.hathitrust.org/cgi/pt?id=uc1.b4049838&view=1up&seq=324) (accessed 18 Sep 2023)