| Business | Phone |
| Arens Engineering 301 Capital St # A1, Yankton 57078 | (605) 665-2002 |
| East River Engineering 1300 W 17th St, Yankton 57078 | (605) 665-3866 |
| Eisenbraun & Assoc Inc 215 Walnut St, Yankton 57078 | (605) 665-8092 |
| Nohr Engineering 307 1/2 Walnut St # 200, Yankton 57078 | (605) 665-1214 |