27 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 46307 | Crown Point | 71,673 |
| 46410 | Merrillville | 39,243 |
| 46342 | Hobart | 32,224 |
| 46312 | East Chicago | 26,022 |
| 46375 | Schererville | 24,188 |
| 46321 | Munster | 23,733 |
| 46322 | Highland | 23,680 |
| 46311 | Dyer | 23,321 |
| 46323 | Hammond | 23,047 |
| 46324 | Hammond | 21,409 |
| 46356 | Lowell | 19,721 |
| 46373 | Saint John | 18,843 |
| 46319 | Griffith | 17,847 |
| 46303 | Cedar Lake | 17,680 |
| 46408 | Gary | 15,747 |
| 46404 | Gary | 15,428 |
| 46320 | Hammond | 14,353 |
| 46405 | Lake Station | 12,184 |
| 46394 | Whiting | 11,894 |
| 46403 | Gary | 10,929 |
| 46327 | Hammond | 10,597 |
| 46406 | Gary | 9,001 |
| 46407 | Gary | 8,577 |
| 46409 | Gary | 7,184 |
| 46402 | Gary | 5,836 |
| 46376 | Schneider | 319 |
| 46377 | Shelby | 45 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 27 ZCTAs in Lake County, Indiana (US Census).