| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Centralia | 1 | 19,543 | 18,387 | 0.87% | 2,502 | 8 | City |
| Chehalis | 2 | 7,823 | 7,489 | 0.76% | 1,347 | 6 | City |
| Winlock | 3 | 2,810 | 1,836 | 6.44% | 831 | 3 | City |
| Napavine | 4 | 2,216 | 1,898 | 2.93% | 766 | 3 | City |
| Morton | 5 | 1,114 | 1,039 | 1.09% | 1,357 | 1 | City |
| Mossyrock | 6 | 813 | 772 | 0.87% | 1,182 | 1 | City |
| Toledo | 7 | 808 | 636 | 4.12% | 1,211 | 1 | City |
| Vader | 8 | 748 | 620 | 2.47% | 805 | 1 | City |
| Pe Ell | 9 | 674 | 643 | 0.75% | 1,140 | 1 | Town |
Centralia is the largest city in Lewis County, with a population of 19,543.
Pe Ell is the smallest city in Lewis County, with a population of 674.
There are 9 cities in Lewis County, Washington.