Special election to fill vacancy caused by death of Patrick V. McNamara. Robert P. Griffin was initially appointed to fill the vacancy and ran in both the special and regular elections.
Source for Popular Vote data: Michigan Secretary of State. Michigan Manual, 1967-1968, Michigan Secretary of State (https://babel.hathitrust.org/cgi/pt?id=mdp.39015071179264&view=1up&seq=534) (accessed 18 Sep 2023)