Lock and Dam No. 24 is a lock and dam located near Clarksville, Missouri around river mile 273.4 on the UpperMississippi River. The main lock is 110 feet (33.5 m) wide and 600 feet (182.9 m) long with its bottom at an elevation of 430 feet. The auxiliary lock is not operational. Normal pool elevation behind the dam is 449 feet. The movable portion of the dam is 1,340 feet (408.4 m) long and consists of 15 submersible, elliptical, tainter gates. A 2,720 feet (829.1 m) submersible earthen dike extends from the movable dam to the Illinois shore. In 2004, the facility was listed in the National Register of Historic Places as Lock and Dam No. 24 Historic District, #04000183 covering 1,027 acres (4.2 km2), 3 buildings, 15 structures, 4 objects.