The Carrollton Viaduct over Gwynn's Falls was the first masonry railroad viaduct constructed in the United States. This structure proved the feasibility of using a viaduct to transport railway vehicles across wide and deep valleys.
Requests for public power in Seattle began in the late 1890s and lead to the voter approval for building the Cedar Falls Water Supply hydroelectric dam plant in 1902. The first municipally developed and owned hydroelectric plant in the United States began operation in October 1904. The facility is situated one-half mile below Cedar Lake (later known as Chester Morse Lake) near North Bend in King County.