Union Electric advertises electric irons in the St. Louis Post-Dispatch in 1911

Foreseeing continuous growth, in 1913 Union Electric Company contracted to buy electricity generated in an innovative way -- through hydroelectricity -- from the newly built Keokuk Dam in Iowa, 150 miles north of St. Louis on the Mississippi River.

Linking the 150 miles between Keokuk and St. Louis marked the greatest distance that power had ever been transmitted in such quantity. In 1925, Union Electric acquired Keokuk Plant, an engineering marvel in its time.