| Zip Code | City | Population ↓ |
|---|---|---|
| 4841 | Rockland | 6,986 |
| 4843 | Camden | 5,221 |
| 4864 | Warren | 4,873 |
| 4862 | Union | 4,130 |
| 4856 | Rockport | 3,636 |
| 4861 | Thomaston | 2,753 |
| 4847 | Hope | 1,795 |
| 4574 | Washington | 1,711 |
| 4860 | Tenants Harbor | 1,590 |
| 4563 | Cushing | 1,464 |
| 4854 | Owls Head | 1,440 |
| 4858 | South Thomaston | 1,371 |
| 4547 | Friendship | 1,145 |
| 4863 | Vinalhaven | 981 |
| 4859 | Spruce Head | 781 |
| 4853 | North Haven | 448 |
| 4855 | Port Clyde | 266 |
| 4851 | Matinicus | 95 |
| 4645 | Isle Au Haut | 43 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 19 ZCTAs in Knox County, Maine (US Census).