| Business | Phone |
| Plumbers & Steamfitters Union 2901 Twin City Dr # 101, Mandan 58554 | (701) 663-0999 |
| Operating Engineers 2901 Twin City Dr # 102, Mandan 58554 | (701) 663-0407 |
| Pace International Union 100 Collins Ave, Mandan 58554 | (701) 663-3163 |
| N D State Building & Constr 2901 Twin City Dr, Mandan 58554 | (701) 663-8821 |
| Iron Workers Local 2901 Twin City Dr # 104, Mandan 58554 | (701) 663-4266 |