| Rank | County | State | Population Density (per sq mi) | Ocean Frontage Type |
|---|---|---|---|---|
| 1 | Washington County | Maine | ~28 | Atlantic - "Down East" coast |
| 2 | Hancock County | Maine | ~45 | Atlantic - includes Acadia region (rural except Bar Harbor) |
| 3 | Waldo County | Maine | ~70 | Penobscot Bay (Atlantic) - note: includes islands |
| 4 | Lincoln County | Maine | ~80 | Atlantic - Boothbay region, mid-coast |
| 5 | Knox County | Maine | ~130 | Atlantic - Rockland, Camden area (more populated) |
| 6 | Sagadahoc County | Maine | ~145 | Atlantic - includes Phippsburg, small coastal towns |
| 7 | Cumberland County | Maine | ~320 | Atlantic - includes Portland (which skews density higher) |
| 8 | York County | Maine | ~220 | Atlantic - southern Maine coast, more developed |
| 9 | Hyde County | North Carolina | ~9** | Atlantic - Outer Banks, very low population but narrow barrier islands |
| 10 | Currituck County | North Carolina | ~100 | Atlantic - northern Outer Banks, very rural |
Note on Hyde County, NC: Its density appears extremely low (~9 per sq mi)