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 2009, it has an estimated population of 582,130 making it the 29th most populous in the United States. It has been referred to as the most environmentally friendly or "green" city in the United States, and the 2nd most in the world. Portland is Oregon's most populous city, and the third most populous city in the Pacific Northwest, after Seattle, Washington, and Vancouver, British Columbia. Approximately two million people live in the Portland metropolitan area, 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. The city and region are noted for strong land-use planning and investment in light rail, supported by Metro, a distinctive regional-government. Portland is known for its large number of microbreweries and microdistilleries, and its coffee fanaticism. It is also the home of the Trail Blazers NBA team. Portland lies in the Marine west coast climate region, marked by warm, dry summers and rainy but temperate winters. This climate is ideal for growing roses, and for more than a century, Portland has been known as "The City of Roses" with many rose gardens—most prominently the International Rose Test Garden.