Ainsworth State Park, State park in Columbia River Gorge, Oregon, US

Ainsworth State Park is a forested area along the Columbia River Gorge with hiking trails, picnic areas, and camping facilities. The site offers direct access to several routes, including the Gorge 400 Trail, and sits within the natural canyon landscape.

The park takes its name from John Churchill Ainsworth (1870–1943), a Portland banker and chairman of the State Highway Commission in 1931–1932, who donated the land in 1933. He was a son of pioneer steamboat operator John Commingers Ainsworth. The park later came under the Oregon Parks and Recreation Department and lies within the Columbia River Gorge National Scenic Area; the Eagle Creek Fire affected it, with limited damage.

The park carries the name of John Churchill Ainsworth (1870–1943), a Portland banker and chairman of the State Highway Commission in 1931–1932, who donated the land in 1933. He was a son of pioneer steamboat operator John Commingers Ainsworth. The park lies beside the Historic Columbia River Highway, and its amphitheater hosts campfire programs in season.

The area offers camping sites with water and electrical connections, walk-in tent areas, and restrooms with running water. Visitors should prepare for mostly shaded trails under trees and know that the best time for exploring is during the warmer season.

The park sits at the eastern edge of a zone known for multiple waterfalls within short distances. Hikers can access Multnomah, Latourell, and Horsetail Falls, which are located in the nearby surroundings.