Johnston County area

Population and density of Johnston County

The Census Bureau estimates that 256,448 people lived in Johnston County on July 1, 2025. That ranks #289 of 3,222 county equivalents nationally and #9 of 100 in North Carolina. Since the April 1, 2020 estimates base of 216,014, the population has grown by 40,434 (+18.7%), compared with +7.2% for North Carolina as a whole.

With 792 square miles of land, that is 324 people per square mile (125 per km²), placing Johnston County #480 nationally for density and #19 in North Carolina. The median county equivalent has 47 people per square mile; the North Carolina median is 116. Put another way, there are about 2 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Johnston County

12 incorporated places lie at least partly in Johnston County. Together they are home to 75,433 people (29.4%); the other 181,015 (70.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Clayton town, with 32,633 residents in the county (the city extends into 1 other county). The county seat, Smithfield town, has 13,114 residents. Among places with at least 1,000 residents in 2020, Four Oaks town grew fastest since then (+33.3%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Johnston County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Johnston County is an outlying county of the Raleigh-Cary, NC Metropolitan Statistical Area. Its 3 county equivalents have 1,595,720 residents on 2,118.7 square miles of land; Johnston County accounts for 37.4% of the land and 16.1% of the residents. By combined land it ranks #148 of 393 metropolitan areas, and #41 by population. It belongs to the Raleigh-Durham-Cary, NC Combined Statistical Area.

ZIP codes

22 ZIP Code Tabulation Areas have land in Johnston County; 11 of them have most of their land inside the county, and the others mainly cover neighboring areas.

27501275042752027524275272752927542275552755727568275692757627577275912759227593275972760327610278632833428366

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Johnston County

Johnston County shares a land border with 6 county equivalents. It has more land than 4 of them. The largest neighbor is Sampson County (945.9 mi²) and the smallest is Wilson County (367.6 mi²). Together with its neighbors, Johnston County forms a block of 4,629.8 mi² of land, of which it holds 17.1%.

How big is Johnston County compared with U.S. states?

Johnston County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.3 times as much. North Carolina’s county land could hold about 61 areas the size of Johnston County.

Another way to picture it: the same land area would fill a square about 28.1 miles (45.3 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Johnston County?

Johnston County has more land than 2,138 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Johnston County at #1,192 nationally by total area, 108 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 0.5%, compared with a national county-equivalent median of 1.2% — 0.7 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Johnston County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.