March 3, 1931
Special Election
Special Election to fill the vacancy created by the resignation of Senator Roy Fellom (SD-21). Senator Fellom had resigned from SD-21 (to which he had been elected in 1928) to assume the SD-14 seat (to which he had been elected in 1930).
| SD-21 | |||
| A. Cummings | Nonpartisan | 2% | Loss |
| Frederick Carsten Gerdes | Nonpartisan | 12.8% | Loss |
| R. Leary | Nonpartisan | 4.3% | Loss |
| A. Lobree | Nonpartisan | 4.8% | Loss |
| Elmer E. Robinson | Nonpartisan | 29.7% | Loss |
| Timothy E. Treacy | Nonpartisan | 36.9% | Win |
| G. Watson | Nonpartisan | 9.4% | Loss |