Multnomah county is the smallest in area but the largest in population due to Portland, the county seat and largest city in Oregon. The county was named after a 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 and are considered to be part of the Chinook tribe. It is also possible that Multnomah is a corruption of nematlnomaq, meaning down river. As of 2001, the county population is 665,810.
 
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