| State: | NV |
| Type: | NV |
| Route: | 320 |
| Alternate Name: | Caselton Mine Loop |
| Map Custom: | yes |
| Map Notes: | SR 320 highlighted in red |
| Length Mi: | 10.674 |
| Length Round: | 3 |
| Length Ref: | [1] |
| Established: | 1976 |
| Direction A: | Southeast |
| Terminus A: | south of Pioche |
| Direction B: | Northwest |
| Terminus B: | north of Pioche |
| Previous Type: | NV |
| Previous Route: | 319 |
| Next Type: | NV |
| Next Route: | 321 |
State Route 320 (SR 320) is a state highway in Lincoln County, Nevada, United States. Known as the Caselton Mine Loop, the highway is a loop route of U.S. Route 93 (US 93) near Pioche serving the Caselton Mining District.