Construction began in 1910 and when completed in 1913 it was the largest capacity, single powerhouse electricity generating plant in the world.
The Power House and spillways are owned and operated by Ameren Missouri and has a 142 MW capacity.
The powerhouse contains 15 generators, originally designed to produce 25 Hz instead of the 60 Hz alternating current used today.
  Keokuk and Hamilton Water Power landed contracts in 1910 to deliver 44.7 MW of electricity to three customers located in St. Louis, MO (more than 100 miles downstream), at a time when no electric power had been transmitted more than a few miles: The Union Electric Light and Power Company, Laclede Gas Company and United Railways Company, which operated the St. Louis Street Railway Company.
 Union Electric Co. purchased the facilities in 1925.
 The 25 Hz generators powered industrial customers and used for the Streetcars in St. Louis, Missouri.

After World War II, a number of modernization improvements were undertaken.
 The 25-cycle generators were progressively converted to 60-cycle generators beginning in 1940s with the final units converted in 2002.
 Electronic automation replacement for some mechanical systems began in 1980s.
 Ameren Missouri, the current powerhouse owner, began replacement and conversion of the original 1913 turbines with more efficient stainless steel turbines.

Today, Keokuk Energy Center remains the largest privately owned and operated dam on the Mississippi River.
 In addition to Lock and Dam No.
19, Lock and Dam No.
1, Lock and Dam No.
2 and the upper St. Anthony Falls dam also produce electricity on the Mississippi River system.
Construction began in 1910 and when completed in 1913 it was the largest capacity, single powerhouse electricity generating plant in the world. The Power House and spillways are owned and operated by Ameren Missouri and has a 142 MW capacity. The powerhouse contains 15 generators, originally designed to produce 25 Hz instead of the 60 Hz alternating current used today.   Keokuk and Hamilton Water Power landed contracts in 1910 to deliver 44.7 MW of electricity to three customers located in St. Louis, MO (more than 100 miles downstream), at a time when no electric power had been transmitted more than a few miles: The Union Electric Light and Power Company, Laclede Gas Company and United Railways Company, which operated the St. Louis Street Railway Company.  Union Electric Co. purchased the facilities in 1925.  The 25 Hz generators powered industrial customers and used for the Streetcars in St. Louis, Missouri.
After World War II, a number of modernization improvements were undertaken.  The 25-cycle generators were progressively converted to 60-cycle generators beginning in 1940s with the final units converted in 2002.  Electronic automation replacement for some mechanical systems began in 1980s.  Ameren Missouri, the current powerhouse owner, began replacement and conversion of the original 1913 turbines with more efficient stainless steel turbines.
Today, Keokuk Energy Center remains the largest privately owned and operated dam on the Mississippi River.  In addition to Lock and Dam No. 19, Lock and Dam No. 1, Lock and Dam No. 2 and the upper St. Anthony Falls dam also produce electricity on the Mississippi River system.
Lock and Dam No. 19