Portland is a city located in the U.S. state of Oregon, near the confluence of the Willamette and Columbia rivers. As of the 2010 Census, it had a population of 583,776, estimated to have reached 587,865 in 2012  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 region, after Seattle, Washington and Vancouver, British Columbia. Approximately 2,289,800 people live in the Portland metropolitan area (MSA), the 19th most populous MSA in the United States.
Portland was incorporated in 1851 near the end of the Oregon Trail and is the county seat of Multnomah County.  The city has a commission-based government headed by a mayor and four other commissioners as well as Metro, a distinctive regional government. The city is noted for its superior land-use planning and investment in light rail. 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.