Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern boundaries respectively. The area was inhabited by many indigenous tribes before the arrival of traders, explorers and settlers who formed an autonomous government in Oregon Country in 1843; the Oregon Territory was created in 1848, and Oregon became the 33rd state on February 14, 1859. Salem is the state's capital and third-most-populous city; Portland is the most populous. Portland is the 30th-largest U.S. city, with a population of 582,130 (2009 estimate) and a metro population of 2,241,841 (2009 estimate), the 23rd-largest U.S. metro area.