Jasper County area

Population and density of Jasper County

The Census Bureau estimates that 38,153 people lived in Jasper County on July 1, 2025. That ranks #1,257 of 3,222 county equivalents nationally and #16 of 99 in Iowa. Since the April 1, 2020 estimates base of 37,816, the population has grown by 337 (+0.9%), compared with +1.5% for Iowa as a whole.

With 730.4 square miles of land, that is 52 people per square mile (20 per km²), placing Jasper County #1,502 nationally for density and #21 in Iowa. The median county equivalent has 47 people per square mile; the Iowa median is 26. Put another way, there are about 12 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 Jasper County

14 incorporated places lie at least partly in Jasper County. Together they are home to 25,538 people (66.9%); the other 12,615 (33.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Newton city, with 15,741 residents in the county. Among places with at least 1,000 residents in 2020, Monroe city grew fastest since then (+2.9%).

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

Metropolitan area

Jasper County is an outlying county of the Des Moines-West Des Moines, IA Metropolitan Statistical Area. Its 6 county equivalents have 758,539 residents on 3,612.7 square miles of land; Jasper County accounts for 20.2% of the land and 5% of the residents. By combined land it ranks #80 of 393 metropolitan areas, and #83 by population. It belongs to the Des Moines-West Des Moines-Ames, IA Combined Statistical Area.

ZIP codes

21 ZIP Code Tabulation Areas have land in Jasper County; 12 of them have most of their land inside the county, and the others mainly cover neighboring areas.

500285005450055501065011250127501355013750141501535016150162501685016950170502085022850232502345023750251

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 Jasper County

Jasper County shares a land border with 6 county equivalents. It has more land than every one of them. The largest neighbor is Poweshiek County (584.9 mi²) and the smallest is Marion County (554.5 mi²). Together with its neighbors, Jasper County forms a block of 4,158.5 mi² of land, of which it holds 17.6%.

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

Jasper County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. Iowa’s county land could hold about 76 areas the size of Jasper County.

Another way to picture it: the same land area would fill a square about 27 miles (43.5 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 Jasper County?

Jasper County has more land than 2,010 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 Jasper County at #1,315 nationally by total area, 103 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% — 0.8 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 Jasper 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.