52 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Milford | 1 | 14,771 | 11,184 | 4.92% | 1,499 | 10 | City |
| Milford | 2 | 14,771 | 11,310 | 4.92% | 1,499 | 10 | City |
| Seaford | 3 | 9,194 | 7,936 | 2.7% | 1,801 | 5 | City |
| Seaford | 4 | 9,194 | 7,982 | 2.7% | 1,801 | 5 | City |
| Georgetown | 5 | 8,324 | 7,150 | 2.79% | 1,658 | 5 | Town |
| Georgetown | 6 | 8,324 | 7,193 | 2.79% | 1,658 | 5 | Town |
| Millsboro | 7 | 8,094 | 6,899 | 2.92% | 1,584 | 5 | Town |
| Millsboro | 8 | 8,094 | 6,943 | 2.92% | 1,584 | 5 | Town |
| Laurel | 9 | 4,519 | 3,873 | 2.82% | 1,631 | 3 | Town |
| Laurel | 10 | 4,519 | 3,896 | 2.82% | 1,631 | 3 | Town |
| Milton | 11 | 3,882 | 3,315 | 2.89% | 2,088 | 2 | Town |
| Milton | 12 | 3,882 | 3,335 | 2.89% | 2,088 | 2 | Town |
| Lewes | 13 | 3,797 | 3,301 | 2.57% | 906 | 4 | City |
| Lewes | 14 | 3,797 | 3,320 | 2.57% | 906 | 4 | City |
| Selbyville | 15 | 3,379 | 2,889 | 2.86% | 942 | 4 | Town |
| Selbyville | 16 | 3,379 | 2,907 | 2.86% | 942 | 4 | Town |
| Long Neck | 17 | 3,234 | 2,869 | 2.67% | 1,172 | 3 | CDP |
| Ocean View | 18 | 3,113 | 2,646 | 2.98% | 1,121 | 3 | Town |
| Ocean View | 19 | 3,113 | 2,663 | 2.98% | 1,121 | 3 | Town |
| Bridgeville | 20 | 2,992 | 2,558 | 2.85% | 621 | 5 | Town |
| Bridgeville | 21 | 2,992 | 2,574 | 2.85% | 621 | 5 | Town |
| Delmar | 22 | 2,337 | 2,027 | 2.59% | 1,229 | 2 | Town |
| Delmar | 23 | 2,337 | 2,040 | 2.59% | 1,229 | 2 | Town |
| Millville | 24 | 2,170 | 1,845 | 2.94% | 852 | 3 | Town |
| Millville | 25 | 2,170 | 1,857 | 2.94% | 852 | 3 | Town |
| Lincoln | 26 | 1,799 | 605 | 7.15% | 638 | 3 | CDP |
| Blades | 27 | 1,367 | 1,171 | 2.78% | 2,472 | 1 | Town |
| Blades | 28 | 1,367 | 1,179 | 2.78% | 2,472 | 1 | Town |
| Rehoboth Beach | 29 | 1,292 | 1,108 | 2.78% | 1,100 | 1 | City |
| Rehoboth Beach | 30 | 1,292 | 1,115 | 2.78% | 1,100 | 1 | City |
| Greenwood | 31 | 1,155 | 989 | 2.85% | 1,455 | 1 | Town |
| Greenwood | 32 | 1,155 | 994 | 2.85% | 1,455 | 1 | Town |
| Bethany Beach | 33 | 1,114 | 951 | 2.86% | 970 | 1 | Town |
| Bethany Beach | 34 | 1,114 | 957 | 2.86% | 970 | 1 | Town |
| Dagsboro | 35 | 1,016 | 869 | 2.83% | 707 | 1 | Town |
| Dagsboro | 36 | 1,016 | 874 | 2.83% | 707 | 1 | Town |
| Frankford | 37 | 930 | 799 | 2.76% | 1,267 | 1 | Town |
| Frankford | 38 | 930 | 805 | 2.76% | 1,267 | 1 | Town |
| Ellendale | 39 | 571 | 490 | 2.7% | 1,344 | 0 | Town |
| Ellendale | 40 | 571 | 493 | 2.7% | 1,344 | 0 | Town |
| South Bethany | 41 | 535 | 457 | 2.88% | 1,064 | 1 | Town |
| South Bethany | 42 | 535 | 460 | 2.88% | 1,064 | 1 | Town |
| Dewey Beach | 43 | 416 | 356 | 2.72% | 1,257 | 0 | Town |
| Dewey Beach | 44 | 416 | 358 | 2.72% | 1,257 | 0 | Town |
| Fenwick Island | 45 | 400 | 342 | 2.83% | 1,208 | 0 | Town |
| Fenwick Island | 46 | 400 | 344 | 2.83% | 1,208 | 0 | Town |
| Bethel | 47 | 274 | 237 | 2.62% | 623 | 0 | Town |
| Bethel | 48 | 274 | 239 | 2.62% | 623 | 0 | Town |
| Henlopen Acres | 49 | 162 | 139 | 2.53% | 635 | 0 | Town |
| Henlopen Acres | 50 | 162 | 140 | 2.53% | 635 | 0 | Town |
| Galestown | 51 | 115 | 114 | 0% | 489 | 0 | Town |
| Galestown | 52 | 115 | 114 | 0% | 489 | 0 | Town |
Milford is the largest city in Sussex County, with a population of 14,771.
Galestown is the smallest city in Sussex County, with a population of 115.
There are 52 cities in Sussex County, Delaware.