Founded in February 2, 1865, Lewis and Clark County is one of 56 counties in the state of Montana. Historically, Lewis and Clark County was one of the 9 original counties. The city of Helena is the county seat. With FIPS code of 49, Lewis and Clark County has a population of 72,223 and area of 3,461 square miles (8,964 km2).
List of all cities in Lewis and Clark County, MT alphabetically
| City/Town | Postal Code | Area Code |
| Augusta, MT | 59410 | 406 |
| Canyon Creek, MT | 59633 | 406 |
| Carroll College, MT | 59625 | 406 |
| City County Building, MT | 59623 | 406 |
| Craig, MT | 59648 | 406 |
| East Helena, MT | 59635 | 406 |
| Fort Harrison, MT | 59636 | 406 |
| Helena, MT | 59601 | 406 |
| 59602 | 406 | |
| 59604 | 406 | |
| 59620 | 406 | |
| 59623 | 406 | |
| 59624 | 406 | |
| 59625 | 406 | |
| 59626 | 406 | |
| Lincoln, MT | 59639 | 406 |
| Marysville, MT | 59640 | 406 |
| State of Montana, MT | 59620 | 406 |
| Wolf Creek, MT | 59648 | 406 |