| ZIP Codes: | 10 ZIP Codes (8 Standard, 2 PO Box, 0 Unique) [See All] |
| Area Code: | 509 |
| Timezone: | Pacific (GMT -08:00) |
| Local Time: | 2:14:15 PM |
| Population: | 211,971 [See All] |
| FIPS: | 53005 |
| CBSA: | Kennewick-Richland, WA |
| Land Area: | 1,801 sq mi |
| Water Area: | 50 sq mi |
| Coordinates: | 46.1853, -119.3904 |
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211,971 residents live across 10 ZIPs covering 1,801 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 181,617 to 211,971 from 2014 to 2024 — a +16.7% change. 8 ZIPs gained residents, 2 lost.
The county's wealthiest ZIP 99353 (West Richland, $121,845 median) and poorest ZIP 99336 (Kennewick, $62,527) are 12.4 miles apart — a 1.9× income gap across local geography.
Median home values vary 1.7× across this county — from $324,400 in 99336 (Kennewick) to $551,500 in 99338 (Kennewick).
Density varies 181× across the county — from 19 people/sq mi in 99350 (Prosser) to 3,368 in 99336 (Kennewick).
Educational attainment ranges from 18.0% bachelor's+ in 99320 (Benton City) to 49.2% in 99352 (Richland) — the breadth of educational profiles across the area.
Within Washington, this is the #10 most populous of 39 counties and ranks #10 for median household income with the #5 fastest decade growth .
Weighted by population, the typical household earns about $91,121 across the county — reflecting what a typical resident sees, not a simple ZIP average.
33.4% of adults age 25+ hold a bachelor's degree or higher (46,175 of 138,451 reporting). The most-educated ZIPs cluster around Richland.
8 Standard delivery, 2 PO Box only, 0 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 99336 | Kennewick | Standard | 50,735 | $62,527 | 15.1 | 1.5% |
| 99352 | Richland | Standard | 37,430 | $100,108 | 25.2 | 31.8% |
| 99337 | Kennewick | Standard | 33,287 | $98,848 | 214.8 | 11.7% |
| 99354 | Richland | Standard | 25,559 | $91,933 | 323.0 | 12.8% |
| 99338 | Kennewick | Standard | 20,633 | $111,042 | 83.8 | 59.8% |
| 99353 | West Richland | Standard | 19,251 | $121,845 | 27.6 | 36.3% |
| 99350 | Prosser | Standard | 14,837 | $81,014 | 797.8 | 3.1% |
| 99320 | Benton City | Standard | 9,879 | $90,102 | 157.2 | 12.4% |
| 99346 | Plymouth | PO Box | 198 | $50,865 | 81.2 | -46.0% |
| 99345 | Paterson | PO Box | 162 | $102,500 | 75.2 | -15.6% |