| ZIP Codes: | 12 ZIP Codes (9 Standard, 3 PO Box, 0 Unique) [See All] |
| Area Codes: | 919 / 984 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 2:12:58 PM |
| Population: | 189,124 [See All] |
| FIPS: | 37101 |
| CBSA: | Raleigh-Cary, NC |
| Land Area: | 702 sq mi |
| Water Area: | 4 sq mi |
| Coordinates: | 35.5420, -78.3309 |
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189,124 residents live across 12 ZIPs covering 702 sq mi, served by 10 distinct USPS-recognized cities.
Population moved from 144,778 to 189,124 from 2014 to 2024 — a +30.6% change. 10 ZIPs gained residents, 0 lost.
The county's wealthiest ZIP 27527 (Clayton, $115,035 median) and poorest ZIP 27577 (Smithfield, $62,758) are 12.3 miles apart — a 1.8× income gap across local geography.
Median home values vary 1.9× across this county — from $207,600 in 27576 (Selma) to $390,200 in 27527 (Clayton).
Density varies 21× across the county — from 101 people/sq mi in 27524 (Four Oaks) to 2,149 in 27568 (Pine Level).
Educational attainment ranges from 16.1% bachelor's+ in 27524 (Four Oaks) to 47.0% in 27527 (Clayton) — the breadth of educational profiles across the area.
Within North Carolina, this is the #14 most populous of 100 counties and ranks #27 for median household income with the #2 fastest decade growth .
On the national stage, Johnston County is and #53 for decade growth .
Weighted by population, the typical household earns about $82,277 across the county — reflecting what a typical resident sees, not a simple ZIP average.
28.4% of adults age 25+ hold a bachelor's degree or higher (36,051 of 126,849 reporting). The most-educated ZIPs cluster around Clayton.
9 Standard delivery, 3 PO Box only, 0 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 27520 | Clayton | Standard | 48,014 | $86,322 | 71.1 | 20.6% |
| 27527 | Clayton | Standard | 39,256 | $115,035 | 44.2 | 103.4% |
| 27577 | Smithfield | Standard | 28,354 | $62,758 | 104.0 | 16.0% |
| 27576 | Selma | Standard | 21,624 | $66,831 | 82.9 | 31.6% |
| 27504 | Benson | Standard | 17,079 | $66,724 | 89.9 | 14.7% |
| 27524 | Four Oaks | Standard | 13,999 | $75,827 | 138.1 | 16.9% |
| 27542 | Kenly | Standard | 9,850 | $66,038 | 90.6 | 10.8% |
| 27569 | Princeton | Standard | 8,833 | $78,850 | 80.7 | 10.9% |
| 27568 | Pine Level | PO Box | 1,542 | $66,071 | 0.7 | 156.1% |
| 27555 | Micro | PO Box | 573 | $44,531 | 0.1 | 22.4% |
| 27593 | Wilsons Mills | PO Box | 0 | — | 0.0 | — |
| 27528 | Clayton | Standard | — | — | 0.0 | — |