THE MARION COUNTY LAND BRIEF
Land in the
Prairie Terraces setting.
Marion County has 1,180.8 square miles of land in Oregon. 7 mapped landscape regions meet across Marion County: Prairie Terraces, Western Cascades Montane Highlands, Western Cascades Lowlands and Valleys, among others.
The Willamette River's floodplains and terraces sit among low hills and scattered buttes. The valley's prairie, oak and riparian landscape differs markedly from the conifer-covered mountains around it.
Regional context: Willamette Valley ↗ · Regional mapping across the county footprint
Where the landscape changes
Marion County intersects 7 mapped regional units. The largest mapped shares are:
- Prairie Terraces30.5%
- Western Cascades Montane Highlands22.5%
- Western Cascades Lowlands and Valleys18.4%
- Valley Foothills15.1%
- Willamette River and Tributaries Gallery Forest7.4%
Cascades in Marion County
Volcanic mountains, deeply cut stream valleys and glaciated high country define the Cascades. Conifer forests change with elevation, giving way to mountain meadows and rocky alpine terrain.
Read the regional source ↗Finding your parcel within Marion County
The atlas lists 27 cities, towns, townships, and Census communities associated with Marion County, including Salem, Keizer, Woodburn. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Marion County by land and water
The Census records 10.2 square miles of water within Marion County, or 0.9% of its total area. That share is close to Marion County’s 0.9%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Marion County has 2,578.3 times the land area of nearby Mehama CDP (0.46 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Clackamas County, Jefferson County, Linn County, Polk County, Wasco County, Yamhill County within Oregon. A tract near one of these lines should be matched to the county identifier on its own records.

