| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Helena | 1 | 35,746 | 32,252 | 1.73% | 2,072 | 17 | City |
| East Helena | 2 | 2,396 | 1,940 | 3.05% | 591 | 4 | City |
Helena is the largest city in Lewis and Clark County, with a population of 35,746.
East Helena is the smallest city in Lewis and Clark County, with a population of 2,396.
There are 2 cities in Lewis and Clark County, Montana.