Cahokia Courthouse, Illinois

Caholia Courthouse, pictured here in the 20th century, was an important place to meet and gather.

University of Illinois Library Digital Collections

Quick Facts

Location:

107 Elm Street, Cahokia, IL 62206

Significance:

Meriwether Lewis and William Clark used Cahokia Courthouse a place to gather information for their journey. All correspondence with President Thomas Jefferson went through the post office at Cahokia.

Designation:

Lewis and Clark National Historic Trail, National Register of Historic Places

MANAGED BY:

State of Illinois

Amenities

5 listed

Benches/Seating, Historical/Interpretive Information/Exhibits, Parking - Auto, Restroom, Water - Drinking/Potable

While wintering at Camp Dubois, Meriwether Lewis and William Clark used Cahokia Courthouse as a base for gathering information.  

Cahokia was the name of the city that flourished here between 1000 and 1350 CE. Many of the people still living nearby descended from those who had built that great city. 

French settlers constructed Cahokia Courthouse in 1740. By 1803, it served as the U.S. territorial courthouse and post office. John Hay, the postmaster, had traded with people in Indigenous communities along the Upper Missouri River. He shared his knowledge with Lewis and Clark. 

Lewis spent much of his time at Cahokia collecting information from various sources. He read travel journals and other publications, as well as interviewed traders, territorial leaders, and Indigenous people passing through. Clark’s journal from the winter also notes several times when visitors from Indigenous communities stopped at Camp Dubois to exchange food and information. 

From these encounters, both men expanded their knowledge of the Upper Missouri region.  

Lewis and Clark also used maps to prepare for their journey. Europeans published these maps using geographic knowledge that Indigenous people shared with them. The Mackay-Evans map, for example, drew on information James Mackay and John Evans received from their Mandan and Hidatsa acquaintances. Throughout their journey, Indigenous hosts drew maps and described trails, routes, shortcuts, and portages to Lewis and Clark. Most of this was not “uncharted” territory—many people knew its terrain and paths intimately and had passed down that knowledge over many generations.

About this article: This article is part of series called “Pivotal Places: Stories from the Lewis and Clark National Historic Trail.”

Lewis and Clark NHT Visitor Centers and Museums

Visitor Centers (shown in orange), High Potential Historic Sites (shown in black), and Pivotal Places (shown in green) along the Lewis and Clark National Historic Trail