Portland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States. Portland is Oregon's most populous city, and the third most populous city in the Pacific Northwest, after Seattle, Washington and Vancouver, British Columbia, Canada. Approximately 2,260,000 people live in the Portland metropolitan area (MSA), the 23rd most populous in the United States.
Portland was incorporated in 1851 and is the county seat of Multnomah County. The city extends west into the Cedar Mill neighborhood in Washington County and south towards Lake Oswego in Clackamas County. With a commission-based government headed by a mayor and four other commissioners, the city and region are noted for strong land-use planning and investment in light rail, supported by Metro, a distinctive regional government. Because of its public transportation networks and efficient land use planning, Portland has been referred to as one of the most environmentally friendly, or "green", cities in the world.