| Business | Phone |
| Yankton County Director-Eqlztn 321 W 3rd St, Yankton 57078 | (605) 665-5962 |
| Yankton County Extension Svc 901 Whiting Dr, Yankton 57078 | (605) 665-3387 |
| Yankton County Government Center Yankton 57078 | (605) 260-4400 |
| Yankton County Museum 610 Summit St, Yankton 57078 | (605) 665-3898 |
| Yankton County Register-Deeds 321 W 3rd St, Yankton 57078 | (605) 665-2422 |
| Yankton County Veterans Office 321 W 3rd St, Yankton 57078 | (605) 665-4696 |