Situated close to northwest Oregon at the confluence of the Willamette and Columbia rivers, it is the county seat of Multnomah County , Oregon's most populous county. As of , [update] Portland's population was ,, [ 11 ] making it the 26th most populous city in the United States, the sixth most populous on the West Coast , and the third most populous in the Pacific Northwest after Seattle and Vancouver. Almost half of Oregon's population resides within the Portland metro area.
Named after Portland, Maine , [ 13 ] which is itself named after England's Isle of Portland , the Oregon settlement began to be populated near the end of the Oregon Trail in the s. Its water access provided convenient transportation of goods, and the timber industry was a major force in the city's early economy.
At the turn of the 20th century, the city had a reputation as one of the most dangerous port cities in the world, and was a hub for organized crime and racketeering ; this reputation dissipated after its economy experienced an industrial boom during World War II , and it became known for its growing liberal and progressive political values from the s onwards, [ 14 ] earning it a reputation as a bastion of counterculture exemplified by the popular slogan " Keep Portland Weird ".
The city operates with a mayorβcouncil government system, guided by a mayor and 12 city councilors , as well as Metro , the only directly elected metropolitan planning organization in the United States. This climate is ideal for growing roses , and Portland has been called the "City of Roses" for over a century. During the prehistoric period, the land that would become Portland was flooded after the collapse of glacial dams from Lake Missoula , in what would later become Montana.
These massive floods occurred during the last ice age and filled the Willamette Valley with to feet 91 to m of water. Before American settlers began arriving in the s, the land was inhabited for many centuries by two bands of indigenous Chinook people β the Multnomah and the Clackamas.
