| Business | Phone |
| International Union-Oper Engrs 4546 Brittania Way, Suitland 20746 | (301) 899-6900 |
| Plumbers Union 5891 Allentown Rd, Suitland 20746 | (301) 899-7861 |
| Seafarer's International Union 5201 Auth Way, Suitland 20746 | (301) 899-0675 |
| Sheet Metal Workers Local 100 4725 Silver Hill Rd, Suitland 20746 | (301) 568-8655 |
| Bricklayers Union 5879 Allentown Rd, Suitland 20746 | (240) 695-9463 |
| District Council 51 3900 James St, Suitland 20746 | (301) 420-0205 |
| Washington Building & Constr 5829 Allentown Rd, Suitland 20746 | (301) 899-8134 |