| ZIP Codes: | 12 ZIP Codes (11 Standard, 1 PO Box, 0 Unique) [See All] |
| Area Codes: | 283 / 326 / 513 / 937 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 2:13:22 PM |
| Population: | 230,451 [See All] |
| FIPS: | 39165 |
| CBSA: | Cincinnati, OH-KY-IN |
| Land Area: | 365 sq mi |
| Water Area: | 6 sq mi |
| Coordinates: | 39.4200, -84.1758 |
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230,451 residents live across 12 ZIPs covering 365 sq mi, served by 12 distinct USPS-recognized cities.
Population moved from 202,153 to 230,451 from 2014 to 2024 — a +14.0% change. 11 ZIPs gained residents, 1 lost.
The county's wealthiest ZIP 45040 (Mason, $133,240 median) and poorest ZIP 45005 (Franklin, $75,399) are 12.3 miles apart — a 1.8× income gap across local geography.
Median home values vary 2.0× across this county — from $216,500 in 45162 (Pleasant Plain) to $440,000 in 45040 (Mason).
Density varies 25× across the county — from 90 people/sq mi in 45054 (Oregonia) to 2,212 in 45065 (South Lebanon).
Educational attainment ranges from 20.2% bachelor's+ in 45005 (Franklin) to 63.0% in 45040 (Mason) — the breadth of educational profiles across the area.
Within Ohio, this is the #11 most populous of 88 counties and ranks #2 for median household income with the #3 fastest decade growth .
Weighted by population, the typical household earns about $111,189 across the county — reflecting what a typical resident sees, not a simple ZIP average.
44.6% of adults age 25+ hold a bachelor's degree or higher (70,069 of 157,133 reporting).
11 Standard delivery, 1 PO Box only, 0 single-entity Unique ZIPs serve this county.
1 ZIP in this county where more than 60% of adults 25+ hold a bachelor's degree — typically college campuses, research enclaves, or tech corridors.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 45040 | Mason | Standard | 59,518 | $133,240 | 28.4 | 14.3% |
| 45036 | Lebanon | Standard | 42,204 | $99,128 | 81.2 | 8.6% |
| 45005 | Franklin | Standard | 32,251 | $75,399 | 37.3 | 6.0% |
| 45039 | Maineville | Standard | 28,335 | $108,794 | 15.5 | 21.1% |
| 45066 | Springboro | Standard | 27,545 | $131,250 | 20.5 | 14.1% |
| 45152 | Morrow | Standard | 14,850 | $123,366 | 48.0 | 32.7% |
| 45068 | Waynesville | Standard | 11,597 | $96,147 | 76.5 | 8.8% |
| 45065 | South Lebanon | Standard | 7,053 | $104,795 | 3.2 | 31.4% |
| 45162 | Pleasant Plain | Standard | 2,754 | $84,722 | 23.0 | 12.2% |
| 45054 | Oregonia | Standard | 2,693 | $99,583 | 29.9 | 19.4% |
| 45034 | Kings Mills | Standard | 968 | $151,875 | 0.9 | -0.9% |
| 45032 | Harveysburg | PO Box | 683 | $66,618 | 0.1 | 89.2% |