Northumberland County area

Population and density of Northumberland County

The Census Bureau estimates that 12,557 people lived in Northumberland County on July 1, 2025. That ranks #2,319 of 3,222 county equivalents nationally and #107 of 133 in Virginia. Since the April 1, 2020 estimates base of 11,835, the population has grown by 722 (+6.1%), compared with +2.9% for Virginia as a whole.

With 191.4 square miles of land, that is 66 people per square mile (25 per km²), placing Northumberland County #1,312 nationally for density and #88 in Virginia. The median county equivalent has 47 people per square mile; the Virginia median is 109. Put another way, there are about 9.8 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 Northumberland County

1 incorporated place lies at least partly in Northumberland County. Together they are home to 76 people (0.6%); the other 12,481 (99.4%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Kilmarnock town, with 76 residents in the county (the city extends into 1 other county).

Metropolitan area

Northumberland County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.

ZIP codes

7 ZIP Code Tabulation Areas have land in Northumberland County; 6 of them have most of their land inside the county, and the others mainly cover neighboring areas.

22432224352247322482225032251122539

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 Northumberland County

Northumberland County shares a land border with 3 county equivalents. It has more land than 1 of them. The largest neighbor is Westmoreland County (229.3 mi²) and the smallest is Lancaster County (133.3 mi²). Together with its neighbors, Northumberland County forms a block of 745.6 mi² of land, of which it holds 25.7%.

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

Northumberland County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 5.4 times as much. Virginia’s county land could hold about 206 areas the size of Northumberland County.

Another way to picture it: the same land area would fill a square about 13.8 miles (22.3 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 Northumberland County?

Northumberland County has more land than 210 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 Northumberland County at #2,875 nationally by total area, 137 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.

Its water share is 33%, compared with a national county-equivalent median of 1.2% — 31.8 percentage points higher. 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 Northumberland 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.