Lewis and Clark State Historic Site lies at the confluence of the the Missouri and Mississippi Rivers near Hartford, Illinois.

The park is for the Lewis and Clark Expedition's winter encampment at Camp River Dubois from December 1803 to May 1804. While camped here, Captains Meriwether Lewis and William Clark trained soldiers, gathered supplies, and prepared for an Expedition that would take them up the Missouri River, across the Rocky Mountains, and down the Columbia River to the Pacific Ocean and back. The Expedition's encampment helped to make the journey a success.

Visitors to the Interpretive Center today can see displays on the preparations for the trip as well as the exciting moments and devastating hardships of the Expedition. A short film details their work. The park has been designated as part of the Lewis and Clark National Historic Trail by the National Park Service.

Multiple replica cabins show what life was like in the early 19th Century. A replica of the Lewis and Clark Expedition camp also shows what camp life was like preparing for the journey.

The Interpretive Center has multiple galleries describing the soldiers and preparation for an expedition. A short film shows visitors more of what those preparations looked like. Many hands-on exhibits encourage visitors to find out more information. A full-scale replica of the the largest boat - the keelboat or barge - is the key piece of the main gallery. Restrooms, water fountains, and gift shop are all available inside.

There is no camping available at the park. Nearby campgrounds are available not too far away.