| ZIP Codes: | 21 ZIP Codes (13 Standard, 8 PO Box, 0 Unique) [See All] |
| Area Codes: | 283 / 326 / 513 / 937 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 2:13:18 PM |
| Population: | 390,313 [See All] |
| FIPS: | 39017 |
| CBSA: | Cincinnati, OH-KY-IN |
| Land Area: | 504 sq mi |
| Water Area: | 5 sq mi |
| Coordinates: | 39.4273, -84.5609 |
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390,313 residents live across 21 ZIPs covering 504 sq mi, served by 15 distinct USPS-recognized cities.
Population moved from 366,317 to 390,115 from 2014 to 2024 — a +6.5% change. 11 ZIPs gained residents, 3 lost.
The county's wealthiest ZIP 45069 (West Chester, $114,631 median) and poorest ZIP 45015 (Hamilton, $48,312) are 8.3 miles apart — a 2.4× income gap across local geography.
Median home values vary 2.9× across this county — from $120,700 in 45015 (Hamilton) to $345,000 in 45069 (West Chester).
Density varies 30× across the county — from 115 people/sq mi in 45064 (Somerville) to 3,402 in 45015 (Hamilton).
Educational attainment ranges from 12.7% bachelor's+ in 45015 (Hamilton) to 52.9% in 45069 (West Chester) — the breadth of educational profiles across the area.
Within Ohio, this is the #8 most populous of 88 counties and ranks #21 for median household income with the #9 fastest decade growth .
Weighted by population, the typical household earns about $82,436 across the county — reflecting what a typical resident sees, not a simple ZIP average.
32.7% of adults age 25+ hold a bachelor's degree or higher (82,427 of 252,335 reporting).
13 Standard delivery, 8 PO Box only, 0 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 45011 | Hamilton | Standard | 75,864 | $91,873 | 61.3 | 10.3% |
| 45044 | Middletown | Standard | 56,217 | $73,732 | 38.6 | 6.5% |
| 45069 | West Chester | Standard | 56,037 | $114,631 | 28.8 | 11.9% |
| 45013 | Hamilton | Standard | 53,998 | $73,633 | 119.2 | 0.9% |
| 45014 | Fairfield | Standard | 45,773 | $75,661 | 25.4 | 3.3% |
| 45042 | Middletown | Standard | 27,652 | $69,520 | 49.9 | 3.8% |
| 45056 | Oxford | Standard | 27,376 | $49,233 | 75.3 | -0.1% |
| 45067 | Trenton | Standard | 15,471 | $81,605 | 19.8 | 9.5% |
| 45050 | Monroe | Standard | 12,248 | $104,282 | 8.7 | 32.8% |
| 45015 | Hamilton | Standard | 11,038 | $48,312 | 3.2 | -8.5% |
| 45053 | Okeana | Standard | 3,718 | $109,148 | 26.8 | 19.1% |
| 45064 | Somerville | Standard | 3,373 | $102,531 | 29.3 | 11.8% |
| 45003 | College Corner | Standard | 839 | $71,250 | 17.5 | 40.3% |
| 45062 | Seven Mile | PO Box | 511 | $52,917 | 0.1 | -24.5% |
| 45055 | Overpeck | PO Box | 198 | — | 0.0 | — |
| 45004 | Collinsville | PO Box | — | — | 0.0 | — |
| 45012 | Hamilton | PO Box | — | — | 0.0 | — |
| 45071 | West Chester | PO Box | — | — | 0.0 | — |
| 45018 | Fairfield | PO Box | — | — | 0.0 | — |
| 45061 | Ross | PO Box | — | — | 0.0 | — |
| 45063 | Shandon | PO Box | — | — | 0.0 | — |