The founders, Joseph Renville, Kenneth McKenzie, William Laidlaw and Daniel Lamont were all British subjects, so they arranged for the company's activities to be officially carried out by William P. Tilton & Co., a New York company operating out of Saint Louis.
In 1823, the company built a trading post, Fort Tilton, by the Mandan villages on the Missouri River.
The axle of the trade was Fort Tecumseh built where the Teton River merges with the Missouri.
Pierre Chouteau Jr. became the chief executive of the Western Department, while Kenneth McKenzie became manager of the Upper Missouri Outfit, operating above the mouth of the Big Sioux River.
McKenzie built Fort Union at the mouth of the Yellowstone River as the Outfit's center of operations.