Cooper County is named for Sarshall Cooper, who was a frontier settler and who was killed by Indians near Arrow Rock in 1814.
Surrounding County Courthouses:
N – Howard County
E – Boone County and Moniteau County
S – Moniteau County and Morgan County
W – Pettis County and Saline County
Created: December 17, 1818 
County Seat:
Boonville 1818 – present
County Courthouse – Boonville
Location: 200 Main Street / High Street
Built: 1912 – 1913
Style: Classical Revival
Architect: Robert George Kirsch of Milwaukee, Wisconsin
Contractor: W J Cochran
Description: The building faces west and is a three story gray colored stone and concrete structure. The rectangular shaped building is located on spacious landscaped grounds in the center of Boonville. The building is 80 feet by 100 feet. The west front has a slightly projecting center section with arched window above the entrance. On the third story is a large window. A wide cornice runs below the roof line and below the second story windows. The roof line is flat. In the interior, the County Circuit Court courtroom is located on the west side of the second story. The building houses the County Circuit Court of the 18th Judicial Circuit..
See: The architect, Robert Geoege Kirsch designed courthouses in Missouri in Adair County, Carroll County, Polk County and Vernon County, in Texas in Hemphill County and Randall County, and in Wisconsin in Oconto County and Waukesha County.
See: The 18th Judicial Circuit includes Cooper County and Pettis County.
History: The county was created in 1818 and Boonville was selected as the county seat. The first courthouse was a two story brick structure built by William C Porter (Potter) and Willis Kempshall at a cost of $9,699 in 1821 to 1823 under the supervision of James Bruffee, Benjamin F Hickox and Robert Wallace. The courthouse was razed. The second courthouse was a two story brick structure built by Seltcer and McCullough in 1838 to 1840 at a cost of approximately $30,000. The third and present courthouse was constructed in 1912 to 1913 at a cost of $95,000.
County Courthouse – Boonville
A
County Circuit Court courtroom
Photos taken 2009 and 2023