Steam and the inexpensive electricity it could produce brought about dramatic technical growth in the United States. Developed during the last century, reliable and efficient steam engines were the forerunners of today's massive generating facilities. A rare survivor of the period, the Pratt facility is the oldest generating plant of its kind in the Northeast and embodies the typical features of engines in a row, open-front marble switchboard, and an observation balcony at street level.
The Port Washington Power Plant of the Wisconsin Electric Company was the most thermally efficient steam power plant in the world for many years following its opening in 1935. Its design reflected the cumulative experience of the utility's engineers in burning pulverized coal at the Oneida Street Plant and the Lakeside Station in Milwaukee.