Black Hawk County area

Population and density of Black Hawk County

The Census Bureau estimates that 131,532 people lived in Black Hawk County on July 1, 2025. That ranks #507 of 3,222 county equivalents nationally and #5 of 99 in Iowa. Since the April 1, 2020 estimates base of 131,146, the population has grown by 386 (+0.3%), compared with +1.5% for Iowa as a whole.

With 565.8 square miles of land, that is 232 people per square mile (90 per km²), placing Black Hawk County #594 nationally for density and #5 in Iowa. The median county equivalent has 47 people per square mile; the Iowa median is 26. Put another way, there are about 2.8 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 Black Hawk County

11 incorporated places lie at least partly in Black Hawk County. Together they are home to 121,619 people (92.5%); the other 9,913 (7.5%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Waterloo city, with 66,919 residents in the county. Among places with at least 1,000 residents in 2020, Hudson city grew fastest since then (+19%).

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

Metropolitan area

Black Hawk County is a central county of the Waterloo-Cedar Falls, IA Metropolitan Statistical Area. Its 3 county equivalents have 169,189 residents on 1,503.1 square miles of land; Black Hawk County accounts for 37.6% of the land and 77.7% of the residents. By combined land it ranks #218 of 393 metropolitan areas, and #268 by population.

ZIP codes

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

506125061350623506265062950634506435064750648506515066750669506705067550701507025070350707

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 Black Hawk County

Black Hawk County shares a land border with 6 county equivalents. It has more land than 2 of them. The largest neighbor is Tama County (721 mi²) and the smallest is Bremer County (435.5 mi²). Together with its neighbors, Black Hawk County forms a block of 4,091.4 mi² of land, of which it holds 13.8%.

How big is Black Hawk County compared with U.S. states?

Black Hawk County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.8 times as much. Iowa’s county land could hold about 99 areas the size of Black Hawk County.

Another way to picture it: the same land area would fill a square about 23.8 miles (38.3 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 Black Hawk County?

Black Hawk County has more land than 1,411 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 Black Hawk County at #1,904 nationally by total area, 93 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 1.2%, compared with a national county-equivalent median of 1.2%. The two percentages are within 0.1 percentage points of each other. 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 Black Hawk 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.