Osborne County area

Osborne County, Kansas covers 894.4 square miles: 892.5 square miles of land and 1.856 square miles of water. Its county seat is Osborne. An estimated 3,285 people lived there in 2025.

Official Census measurements · GEOID 201412026 Gazetteer · retrieved September 27, 2026
Land area892.5 mi²
Water area1.856 mi²
Population (2025)3,285
People per mi²3.7

County outline

Generalized outline of Osborne County, Kansas
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Osborne County is located

Osborne County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 99.8% of Osborne County’s measured area and water for 0.2%. Its combined area converts to 2,316.4 square kilometers or approximately 572,398 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land892.5162,311.606571,210.2
Water1.8564.8071,187.8
Total894.3722,316.413572,398.1

How Osborne County compares

By original Census land area, Osborne County ranks #32 of 105 in Kansas and #884 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 1.223 times the Kansas county-equivalent median of 729.7 square miles. It accounts for 1.1% of the combined county land area in the state.

See the complete Kansas ranking · What counts as a county equivalent?

Population and density of Osborne County

The Census Bureau estimates that 3,285 people lived in Osborne County on July 1, 2025. That ranks #3,014 of 3,222 county equivalents nationally and #78 of 105 in Kansas. Since the April 1, 2020 estimates base of 3,491, the population has declined by 206 (−5.9%), compared with +1.3% for Kansas as a whole.

With 892.5 square miles of land, that is 3.7 people per square mile (1.4 per km²), placing Osborne County #2,932 nationally for density and #82 in Kansas. The median county equivalent has 47 people per square mile; the Kansas median is 8.1. Put another way, there are about 174 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate3,4873,4833,4853,4203,3413,285
Change—−4+2−65−79−56

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 Osborne County

5 incorporated places lie at least partly in Osborne County. Together they are home to 2,465 people (75%); the other 820 (25%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Osborne city, with 1,249 residents in the county.

Incorporated placePopulation 2025Since 2020Land mi²
Osborne cityCounty seat1,249−5.7%1.539
Downs city759−5.7%1.12
Natoma city285−6.3%0.422
Alton city91−7.1%0.309
Portis city81−6.9%0.261

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

Metropolitan area

Osborne 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

12 ZIP Code Tabulation Areas have land in Osborne County; 5 of them have most of their land inside the county, and the others mainly cover neighboring areas.

674306743767473674746748567623676486764967651676586767367675

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 Osborne County

Osborne County shares a land border with 7 county equivalents. It has more land than 4 of them. The largest neighbor is Jewell County (910 mi²) and the smallest is Mitchell County (701.8 mi²). Together with its neighbors, Osborne County forms a block of 6,795.9 mi² of land, of which it holds 13.1%.

Map of Osborne County and the 7 county equivalents that border it Rooks County, Kansas: 890.5 mi² landRussell County, Kansas: 886.3 mi² landSmith County, Kansas: 895.5 mi² landMitchell County, Kansas: 701.8 mi² landLincoln County, Kansas: 719.4 mi² landJewell County, Kansas: 910 mi² landEllis County, Kansas: 899.9 mi² land
Osborne County (dark) and its bordering county equivalents. Select a neighbor to open its profile. Drawn from the 2025 Census cartographic boundaries in an equal-area projection. How borders are determined.
Bordering county equivalentLand mi²Size vs. OsborneCompare
Jewell County910about the sameCompare
Ellis County899.9about the sameCompare
Smith County895.5about the sameCompare
Rooks County890.5about the sameCompare
Russell County886.3about the sameCompare
Lincoln County719.41.2× smallerCompare
Mitchell County701.81.3× smallerCompare

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

Osborne County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.2 times as much. Kansas’s county land could hold about 92 areas the size of Osborne County.

Land area: Osborne County and the closest-sized states
Osborne County892.5 mi²
Rhode Island1,033.9 mi²

Another way to picture it: the same land area would fill a square about 29.9 miles (48.1 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 Osborne County?

Osborne County has more land than 2,338 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Osborne County892.5 mi²
Kansas median729.7 mi²
National median604.5 mi²

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 Osborne County at #998 nationally by total area, 114 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 0.2%, compared with a national county-equivalent median of 1.2% — 1 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 Osborne County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#883Scott County, Arkansas892.9Compare
#884Osborne County, Kansas892.5This county
#885Lynn County, Texas891.9Compare

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.

Representative coordinates

The Census internal point is 39.348261, -98.767942. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.

Source and precision

U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 2,311,604,913 m²; AWATER: 4,806,274 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How big is Osborne County?

Osborne County, Kansas has 892.5 square miles (2,311.6 km²) of land and 1.856 square miles of water, for a total area of 894.4 square miles. It ranks #884 of 3,222 U.S. county equivalents by land area.

Is Osborne County the largest county in Kansas?

No. Osborne County ranks #32 of 105 in Kansas by land area. The largest is Butler County, with 1,429.7 square miles of land.

What counties border Osborne County?

Osborne County shares a land border with Rooks County, Russell County, Smith County, Mitchell County, Lincoln County, Jewell County, and Ellis County.

What is the population of Osborne County?

The Census Bureau estimates Osborne County had 3,285 residents on July 1, 2025, ranking #3,014 of 3,222 county equivalents. That is 3.7 people per square mile of land.

What is the county seat of Osborne County?

The county seat of Osborne County is Osborne.

What cities and towns are in Osborne County?

Osborne County has 5 incorporated places. The most populous are Osborne city, Downs city, Natoma city, Alton city, and Portis city; 820 residents live outside any incorporated place.

Is Osborne County part of a metropolitan area?

No. Osborne County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.

How many ZIP codes are in Osborne County?

12 ZIP Code Tabulation Areas have land in Osborne County, and 5 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

How does Osborne County compare with U.S. states?

It has less land than every state. Rhode Island, the smallest, has 1.2 times as much land.

How many acres of land are in Osborne County?

The land measurement converts to approximately 571,210 acres. Including water, total area is approximately 572,398 acres. One square mile equals 640 acres.

Why might another source show a different area?

Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.

Can this establish a property boundary?

No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.

Cite this county

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