The building housed the equipment which generated the electricity for Washington's transportation system from about 1911 to 1943.

The following information is from the Georgetown Spectator, July 27, 1967: "The Capital Traction Co. built the power plant in 1910-11 to provide power for its streetcars, previously drawn by horses. It was built to be grand and stately by the owners of the firm, Georgetown residents, who were well aware of its importance in the heart of the Georgetown waterfront.

The Delaware Street Tramway Power Substation is significant for its association with the growth and development of Denver's tramway trolley system, a major transportation system during the first half of the 20th century. This substation was instrumental in the conversion of the system from cable power to effective electrical power. It is more stylistically impressive and retains a greater degree of historic integrity than do the other remaining structures believed to have been substations. The building was later (1964?) converted to a coin stamping plant for the Denver Mint.

The Shoshone complex is significant for being one of the earliest hydroelectric plants on the Colorado River and one of the largest in the Rocky Mountain Region to depend upon the flow of a river for its source of power rather than on the stored water of a reservoir. It is also significant as a remarkable engineering accomplishment in terms of the physical difficulties of construction within Glenwood Canyon and the scale of the undertaking.