Multnomah County ( ) is one of 36 counties in the U.S. state of Oregon. Though smallest in area, it is the most populous as its county seat, Portland, is the state's largest city. The county is likely named after Native American people first recorded in the journals of the Lewis and Clark Expedition, Mulknomans, who lived in a village on the east side of present-day Sauvie Island. (An alternative theory holds that Multnomah is a corruption of nematlnomaq, meaning down river.) In 2000, the county's population was 660,486.