27 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 46307 | Crown Point | 71,418 |
| 46410 | Merrillville | 38,803 |
| 46342 | Hobart | 32,525 |
| 46312 | East Chicago | 26,158 |
| 46375 | Schererville | 24,012 |
| 46322 | Highland | 23,749 |
| 46321 | Munster | 23,733 |
| 46311 | Dyer | 23,405 |
| 46323 | Hammond | 23,184 |
| 46324 | Hammond | 21,433 |
| 46356 | Lowell | 19,396 |
| 46373 | Saint John | 18,509 |
| 46319 | Griffith | 17,683 |
| 46303 | Cedar Lake | 16,910 |
| 46404 | Gary | 16,846 |
| 46408 | Gary | 15,571 |
| 46320 | Hammond | 14,097 |
| 46394 | Whiting | 12,141 |
| 46405 | Lake Station | 11,509 |
| 46327 | Hammond | 10,797 |
| 46403 | Gary | 10,697 |
| 46407 | Gary | 8,889 |
| 46406 | Gary | 8,513 |
| 46409 | Gary | 7,072 |
| 46402 | Gary | 5,636 |
| 46376 | Schneider | 280 |
| 46377 | Shelby | 31 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 27 ZCTAs in Lake County, Indiana (US Census).