Lewiston is a city located in northwestern Idaho. It is situated in Nez Perce County, near the border with the state of Washington. The city is located at the confluence of the Snake River and Clearwater River. Lewiston had an estimated population of around 32,000 residents in 2021.

Hells Gate lies on river bottom left over from the great ice age floods about 15,000 years ago. At the south end of the park are basaltic columns from the Pomona flows 14 million years ago.