The Willamette Valley (/wɨˈlæmɨt/) is a 150-mile (240 km) long valley in the U.S. state of Oregon in the Pacific Northwest region of the United States. The valley forms the cultural and political heart of Oregon and is home to approximately 70 percent of its population including Portland, its largest city, as well as Salem, the state capital. The Willamette River flows the entire length of the valley, depositing highly fertile alluvial soils across its broad, flat plain.