The Dalles is a city located in Wasco County, Oregon, United States. It is situated on the Columbia River, just east of the Cascade Mountains and the city of Hood River. The Dalles is the largest city and county seat of Wasco County, and is the second-largest city in the state of Oregon after Oregon City. The city's name comes from the French word for 'TRENCH' or 'CHANNEL, ' referring to the narrows of the Columbia River.