Oregon County Map: All 36 Counties

West of the Cascade Mountains, the Willamette Valley (Multnomah, Washington, Clackamas, Lane, Marion) contains over 70% of Oregon's population. Washington County anchors the "Silicon Forest" corporate campuses of Intel and Nike, while Marion County houses the state capital in Salem.

East of the Cascades, 18 counties stretch across the Columbia Plateau and Great Basin. Harney County covers 10,135 square miles of high desert sagebrush, Steens Mountain fault blocks, and the Malheur National Wildlife Refuge, but holds only about 7,400 residents.

Federal agencies—including the Bureau of Land Management (BLM) and U.S. Forest Service—own over 53% of Oregon's total land area, rising to more than 75% in counties like Harney and Malheur. This federal footprint limits private property tax revenues, making rural county road and emergency budgets heavily reliant on federal O&C timber harvest revenue shares and PILT payments.

Under Article VII, Section 12 of the original 1859 Oregon Constitution, counties were governed by a County Court composed of a County Judge and two county commissioners. While judicial duties were gradually transferred to state circuit courts, six eastern counties—Baker, Gilliam, Grant, Harney, Sherman, and Wheeler—continue to elect a "County Judge" who presides over county administrative meetings and prepares the county budget.

In 1973, Oregon enacted landmark land-use legislation: Senate Bill 100, championed by Governor Tom McCall. SB 100 mandated that every county and city establish an Urban Growth Boundary (UGB) to protect prime agricultural and forest lands from suburban sprawl.

The state Land Conservation and Development Commission (LCDC) oversees county comprehensive land use plans, creating one of the strictest land conservation regimes in the nation.