Osage County is a county located in the central portion of the U.S. state of Missouri. Its county seat is Linn, also known as the “mile long city”. The county, originally part of Gasconade County, was organized January 29, 1841 by Hon. A. Alexander of Gasconade County when he proposed the act which was passed and approved creating Osage County. The name was derived from the French, “Oua Chage”, and through the practice of spelling names as they sounded resulted in Osage. The territory now Osage County was the hunting ground of the Delaware, Shawnee and a large, strong tribe, of Osage Indians. The Indians were not only good hunters, they raised quantities of Indian corn. Most of their activities were confined to the rivers and streams and they were of a peaceful nature.
Now, Osage County Seat in Linn consists of two buildings. The Courthouse located at 106 E. Main Street with the offices of the Sheriff/Jail, Prosecuting Attorney and the Circuit Clerk currently reside.
The Osage County Administration Building also known as the Annex Building is located at 205 E. Main Street with the offices of 911/Emergency Management on the lower lever, Health Department, Assessor, Collector, and Recorder on the main floor and the Treasurer, County Clerk, Commission and University of Missouri Extension located on the second floor.