Built by the Redlands Electric Light and Power Company, the Mill Creek No. 1 hydroelectric plant began operating on September 7, 1893, in Redlands, California. It was the first installation to use three-phase alternating current for a commercial application, and proved decisive for the widespread adoption of three-phase power throughout the United States, marking the shift from experimental demonstration (Lauffen-Frankfurt, 1891) to stable commercial deployment.