Portland is a city located in the Northwestern United States, near the confluence of the Willamette and Columbia rivers in the state of Oregon. As of July 2008, it has an estimated population of 575,930, making it the thirtieth most populous in the United States, and has been referred to as the greenest city in the United States. Portland is Oregon's most populous city, and the third most populous city in the Pacific Northwest, after Vancouver, British Columbia, and Seattle, Washington. Approximately two million people live in the Portland metropolitan area (MSA), the 23rd most populous in the United States as of July 2006.
Portland was incorporated in 1851 and is the county seat of Multnomah County. The city extends slightly into Washington County to the west and Clackamas County to the south. It is governed by a commission-based government headed by a mayor and four other commissioners.