Pennington County area

Population and density of Pennington County

The Census Bureau estimates that 116,792 people lived in Pennington County on July 1, 2025. That ranks #555 of 3,222 county equivalents nationally and #2 of 66 in South Dakota. Since the April 1, 2020 estimates base of 109,231, the population has grown by 7,561 (+6.9%), compared with +5.5% for South Dakota as a whole.

With 2,776.8 square miles of land, that is 42 people per square mile (16 per km²), placing Pennington County #1,706 nationally for density and #7 in South Dakota. The median county equivalent has 47 people per square mile; the South Dakota median is 5.7. Put another way, there are about 15 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 Pennington County

9 incorporated places lie at least partly in Pennington County. Together they are home to 92,073 people (78.8%); the other 24,719 (21.2%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Rapid City city, with 80,589 residents in the county. Among places with at least 1,000 residents in 2020, Box Elder city grew fastest since then (+19%).

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

Metropolitan area

Pennington County is a central county of the Rapid City, SD Metropolitan Statistical Area. Its 3 county equivalents have 156,934 residents on 7,804.6 square miles of land; Pennington County accounts for 35.6% of the land and 74.4% of the residents. By combined land it ranks #20 of 393 metropolitan areas, and #285 by population. It belongs to the Rapid City-Spearfish, SD Combined Statistical Area.

ZIP codes

20 ZIP Code Tabulation Areas have land in Pennington County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.

5770157702577035770657718577195772557730577325774457745577505775157761577675777557780577905779182701

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 Pennington County

Pennington County shares a land border with 7 county equivalents, including 1 in Wyoming. It has more land than 6 of them. The largest neighbor is Meade County (3,470.9 mi²) and the smallest is Lawrence County (800.1 mi²). Together with its neighbors, Pennington County forms a block of 16,770.7 mi² of land, of which it holds 16.6%.

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

Pennington County has more land than 2 of the 50 states. It is about 1.4 times the land area of Delaware (1,948.6 mi²), while Connecticut, the next larger state, has 1.7 times as much land (4,842.5 mi²). South Dakota’s county land could hold about 27 areas the size of Pennington County.

Another way to picture it: the same land area would fill a square about 52.7 miles (84.8 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 Pennington County?

Pennington County has more land than 3,035 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 Pennington County at #204 nationally by total area, 17 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 0.3%, compared with a national county-equivalent median of 1.2% — 0.9 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 Pennington 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.