1978Final results
1978 election for South Dakota Legislative District 15
South Dakota State Senate · South Dakota
Donald C. Peterson (R) won with 60.0% of the vote, defeating Larry I. Rupiper (D) by 20.1 points.
Donald C. PetersonRepublican · winner
60.0%4,016
Larry I. RupiperDemocrat
40.0%2,674
6,690 votes
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET
The seat over time
D − R margin in this seat's races around 1978
Races before and after
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET