Clackamas County area

Clackamas County, Oregon covers 1,883 square miles: 1,870.7 square miles of land and 12.3 square miles of water. Its county seat is Oregon City. An estimated 426,280 people lived there in 2025.

Official Census measurements · GEOID 410052026 Gazetteer · retrieved September 27, 2026
Land area1,870.7 mi²
Water area12.3 mi²
Population (2025)426,280
People per mi²228

County outline

Generalized outline of Clackamas County, Oregon
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 Clackamas County is located

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

Area breakdown

Land accounts for 99.3% of Clackamas County’s measured area and water for 0.7%. Its combined area converts to 4,877 square kilometers or approximately 1,205,129 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land1,870.7124,845.1221,197,255.7
Water12.30231.8627,873.3
Total1,883.0144,876.9841,205,129

How Clackamas County compares

By original Census land area, Clackamas County ranks #18 of 36 in Oregon and #306 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 1.024 times the Oregon county-equivalent median of 1,826.2 square miles. It accounts for 1.9% of the combined county land area in the state.

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

Population and density of Clackamas County

The Census Bureau estimates that 426,280 people lived in Clackamas County on July 1, 2025. That ranks #181 of 3,222 county equivalents nationally and #3 of 36 in Oregon. Since the April 1, 2020 estimates base of 421,429, the population has grown by 4,851 (+1.2%), compared with +0.9% for Oregon as a whole.

With 1,870.7 square miles of land, that is 228 people per square mile (88 per km²), placing Clackamas County #600 nationally for density and #4 in Oregon. The median county equivalent has 47 people per square mile; the Oregon median is 25. Put another way, there are about 2.8 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate422,483423,877423,098424,076425,245426,280
Change—+1,394−779+978+1,169+1,035

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 Clackamas County

16 incorporated places lie at least partly in Clackamas County. Together they are home to 241,844 people (56.7%); the other 184,436 (43.3%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Oregon City city, with 38,175 residents in the county. By land, Portland city is the largest at 133.5 mi² across all its counties. Among places with at least 1,000 residents in 2020, Estacada city grew fastest since then (+31.7%).

Incorporated placePopulation 2025Since 2020Land mi²
Oregon City cityCounty seat38,175+1.5%10.1
Lake Oswego cityAlso in 2 other counties37,220−2.6%10.9
Happy Valley city28,916+23.5%12
West Linn city26,567−2.9%7.43
Wilsonville cityAlso in 1 other county24,523−0.1%7.716
Milwaukie cityAlso in 1 other county22,114+4.5%4.993
Canby city18,004−0.9%4.773
Sandy city13,323+5.4%3.692
Gladstone city11,865−1.4%2.399
Molalla city10,104−1.3%2.507
Estacada city5,814+31.7%2.648
Tualatin cityAlso in 1 other county3,192+1.3%8.418
Portland cityAlso in 2 other counties850−0.5%133.5
Johnson City city554+2.4%0.065
Rivergrove cityAlso in 1 other county489−1.4%0.173
Show the other 1 places
NamePopulation 2025Since 2020Land mi²
Barlow city134+0.8%0.052

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

Metropolitan area

Clackamas County is a central county of the Portland-Vancouver-Hillsboro, OR-WA Metropolitan Statistical Area. Its 7 county equivalents have 2,542,282 residents on 6,687.4 square miles of land; Clackamas County accounts for 28% of the land and 16.8% of the residents. By combined land it ranks #28 of 393 metropolitan areas, and #26 by population. It belongs to the Portland-Vancouver-Salem, OR-WA Combined Statistical Area.

County equivalentPopulation 2025Land mi²
Multnomah County795,391431
Washington County611,708724.3
Clark CountyWashington532,119628.5
Clackamas County426,2801,870.7
Yamhill County110,024715.9
Columbia County54,091658.7
Skamania CountyWashington12,6691,658.3

ZIP codes

37 ZIP Code Tabulation Areas have land in Clackamas County; 24 of them have most of their land inside the county, and the others mainly cover neighboring areas.

97002970049700997011970139701597017970199702297023970279702897032970349703597038970429704597049970559706297067970689707097071970809708697089971329714097202972069721997222972679736297375

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 Clackamas County

Clackamas County shares a land border with 6 county equivalents. It has more land than 5 of them. The largest neighbor is Wasco County (2,381.1 mi²) and the smallest is Multnomah County (431 mi²). Together with its neighbors, Clackamas County forms a block of 7,826.1 mi² of land, of which it holds 23.9%.

Map of Clackamas County and the 6 county equivalents that border it Marion County, Oregon: 1,180.8 mi² landMultnomah County, Oregon: 431 mi² landWasco County, Oregon: 2,381.1 mi² landHood River County, Oregon: 522.2 mi² landWashington County, Oregon: 724.3 mi² landYamhill County, Oregon: 715.9 mi² land
Clackamas 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. ClackamasCompare
Wasco County2,381.11.3× largerCompare
Marion County1,180.81.6× smallerCompare
Washington County724.32.6× smallerCompare
Yamhill County715.92.6× smallerCompare
Hood River County522.23.6× smallerCompare
Multnomah County4314.3× smallerCompare

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

Clackamas County has more land than 1 of the 50 states. It is about 1.8 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1 times as much land (1,948.6 mi²). Oregon’s county land could hold about 51 areas the size of Clackamas County.

Land area: Clackamas County and the closest-sized states
Rhode Island1,033.9 mi²
Clackamas County1,870.7 mi²
Delaware1,948.6 mi²

Another way to picture it: the same land area would fill a square about 43.3 miles (69.6 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 Clackamas County?

Clackamas County has more land than 2,916 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Clackamas County1,870.7 mi²
Oregon median1,826.2 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 Clackamas County at #348 nationally by total area, 42 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 0.7%, compared with a national county-equivalent median of 1.2% — 0.5 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 Clackamas County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#305Klickitat County, Washington1,871.6Compare
#306Clackamas County, Oregon1,870.7This county
#307Summit County, Utah1,870.7Compare

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 45.160493, -122.195127. 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: 4,845,121,430 m²; AWATER: 31,861,093 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 Clackamas County?

Clackamas County, Oregon has 1,870.7 square miles (4,845.1 km²) of land and 12.3 square miles of water, for a total area of 1,883 square miles. It ranks #306 of 3,222 U.S. county equivalents by land area.

Is Clackamas County the largest county in Oregon?

No. Clackamas County ranks #18 of 36 in Oregon by land area. The largest is Harney County, with 10,134.5 square miles of land.

What counties border Clackamas County?

Clackamas County shares a land border with Marion County, Multnomah County, Wasco County, Hood River County, Washington County, and Yamhill County.

What is the population of Clackamas County?

The Census Bureau estimates Clackamas County had 426,280 residents on July 1, 2025, ranking #181 of 3,222 county equivalents. That is 228 people per square mile of land.

What is the county seat of Clackamas County?

The county seat of Clackamas County is Oregon City.

What cities and towns are in Clackamas County?

Clackamas County has 16 incorporated places. The most populous five are Oregon City city, Lake Oswego city, Happy Valley city, West Linn city, and Wilsonville city; 184,436 residents live outside any incorporated place.

Is Clackamas County part of a metropolitan area?

Yes. It is a central county of the Portland-Vancouver-Hillsboro, OR-WA Metropolitan Statistical Area, which has 7 county equivalents and 2,542,282 residents.

How many ZIP codes are in Clackamas County?

37 ZIP Code Tabulation Areas have land in Clackamas County, and 24 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

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

It has more land than 1 of the 50 states, including Rhode Island (1,033.9 square miles of land).

How many acres of land are in Clackamas County?

The land measurement converts to approximately 1,197,256 acres. Including water, total area is approximately 1,205,129 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

Download the complete CSV or JSON dataset