| Zip Code | City | Population ↓ |
|---|---|---|
| 19720 | New Castle | 60,514 |
| 19702 | Newark | 56,571 |
| 19711 | Newark | 49,746 |
| 19709 | Middletown | 48,954 |
| 19701 | Bear | 44,553 |
| 19805 | Wilmington | 39,610 |
| 19808 | Wilmington | 38,107 |
| 19713 | Newark | 29,952 |
| 19802 | Wilmington | 26,065 |
| 19810 | Wilmington | 25,569 |
| 19803 | Wilmington | 21,437 |
| 19804 | Wilmington | 17,986 |
| 19707 | Hockessin | 17,011 |
| 19801 | Wilmington | 16,545 |
| 19703 | Claymont | 16,376 |
| 19809 | Wilmington | 15,529 |
| 19734 | Townsend | 14,026 |
| 19806 | Wilmington | 10,273 |
| 19807 | Wilmington | 7,846 |
| 19717 | Newark | 6,129 |
| 19706 | Delaware City | 1,984 |
| 19730 | Odessa | 558 |
| 19732 | Rockland | 364 |
| 19731 | Port Penn | 328 |
| 19733 | Saint Georges | 173 |
| 19710 | Montchanin | 26 |
| 19736 | Yorklyn | 17 |
| 19735 | Winterthur | 0 |
| 19716 | Newark | 0 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 29 ZCTAs in New Castle County, Delaware (US Census).