Lock and Dam No. 21

Lock and Dam No. 21 ( lock and dam No. 21) is one of 29 dams that enable navigation on the upper Mississippi. Built between 1933 and 1938 by the United States Army Corps of Engineers combined building is located in Quincy in Adams County, Illinois. On the opposite right bank of the Marion County is located in Missouri. In 2004, the Lock and Dam No. was. 21 Historic District was added to the NRHP.

Barrage

To barrage include a 426.7 m long stone dam on the Missouri side and a 385.6 m long variable part, which consists of a ten-part segment weir and three jam rolls.

The dam height is 9 feet (2.70 m). The purpose of the weir is not the flood, but the damming of the Mississippi for navigation.

Lock

The lock is 182.9 m long and 33.5 m wide. Next to it is a second, but not completed smaller airlock chamber.