Marion County is one of the 36 counties in the U.S. state of Oregon. The population was 315,335 at the 2010 census, making it the fifth-most populous county in Oregon. The county seat is Salem, which is also the state capital of Oregon. The county was originally named the Champooick District, after Champoeg (earlier Champooick), a meeting place on the Willamette River. On September 3, 1849, the territorial legislature renamed it in honor of Francis Marion, a Continental Army general from South Carolina who served in the American Revolutionary War.

Marion County is part of the Salem, OR Metropolitan Statistical Area, which is also included in the Portland-Vancouver-Salem, OR-WA Combined Statistical Area. It is located in the Willamette Valley.

Marion County is among the 24 of Oregon’s 36 counties that operate under a board of commissioners (BOC) of three members elected countywide to 4-year terms. In Marion County, these are partisan races. Commissioners, who are full-time, salaried officials, have executive, legislative, and quasi-judicial powers (the latter in land-use cases). The Board of Commissioners serves as the governing body. The commissioners elect their chair annually; in practice, in Marion County, the chair rotates annually. The BOC is responsible for accepting funds from sources outside the county, strategic planning, and enacting ordinances as needed to carry out plans and serve the public. The BOC also prepares a county budget in cooperation with the elected heads of the various departments. The BOC is required by law to appoint a Budget Officer who presents a budget to the Budget Committee composed of the Commissioners and three public members. County commissioners appoint and oversee non-elected department heads, officers, boards, and commissions.

In addition to the Board of Commissioners, the county has the following non-partisan positions that are elected in county-wide elections for four-year terms: Assessor, Clerk, Treasurer, District Attorney, Sheriff, and Justices of the Peace. These officers are not accountable to the Board of Commissioners although they work with the commissioners in establishing a county budget. All are full-time, paid county officers.

County Commission (three commissioners)
Commissioner: Kevin Cameron
Commissioner: Sam Brentano
Commissioner: Colm Willis
District Attorney: Paige Clarkson
Sheriff: Joe Kast
Assessor: Tom Rohlfing
Clerk: Bill Burgess
Treasurer: Laurie Steele
Justice of the Peace: Janice Zyryanoff