Post Offices List in Colusa County, California:
| Arbuckle Post Office | 415 5th St, Arbuckle, CA 95912 |
| Colusa Post Office | 357 Market St, Colusa, CA 95932 |
| Grimes Post Office | 170 Main St, Grimes, CA 95950 |
| Maxwell Post Office | 260 Oak St, Maxwell, CA 95955 |
| Princeton Post Office | 149 Commercial St, Princeton, CA 95970 |
| Stonyford Post Office | 259 Market St, Stonyford, CA 95979 |
| Williams Post Office | 801 E St, Williams, CA 95987 |