| Business | Phone |
| Custer 1881 Courthouse Museum 411 Mount Rushmore Rd, Custer 57730 | (605) 673-2443 |
| Custer County Commissioners 447 Crook St, Custer 57730 | (605) 673-8167 |
| Custer County Communications 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8176 |
| Custer County Community Nurse 447 Crook St, Custer 57730 | (605) 673-2847 |
| Custer County Cooperative Ext 447 Crook St, Custer 57730 | (605) 673-8177 |
| Custer County Equalization Dir 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8170 |
| Custer County Information 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8100 |
| Custer County Planning Office 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8174 |
| Custer County Register-Deeds 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8171 |
| Custer County Veterans Svc 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8123 |
| Custer County Weed Inspector 420 Mount Rushmore Rd, Custer 57730 | (605) 673-8129 |