what river forms part of the border between two northwestern states and flows into pacific ocean
Columbia River The Columbia River is the largest river in the Pacific Northwest region of North America.[9] The river rises in the Rocky Mountains of British Columbia, Canada. It flows northwest and then south into the US state of Washington, then turns west to form most of the border between Washington and the state of Oregon before emptying into the Pacific Ocean. The river is 1,243 miles (2,000Â km) long, and its largest tributary is the Snake River. Its drainage basin is roughly the size of France and extends into seven US states and a Canadian province. The fourth-largest river in the United States by volume, the Columbia has the greatest flow of any North American river entering the Pacific.
Orange River At the western point of the Free State, southwest of Kimberley, the Orange meets with its main tributary, the Vaal River, which itself forms much of the northern border of the province. From here the river flows further westward through the arid wilderness of the southern Kalahari region and Namaqualand in the Northern Cape Province to meet with Namibia at the 20th degree of east longitude. From here it flows westward for 550 km,[6] forming the international border between the province and Namibia's ǁKaras Region. On the border, the river passes the town of Vioolsdrif, the main border post between South Africa and Namibia.