At the western edge of the American prairie, just east of the Rocky Mountains, lies a collection of electrical resources that string together the United States power system. Seven, back-to-back,
high-voltage direct-current (HVDC) facilities enable about 1,400 megawatts (MW) of electricity to flow between the Eastern and Western Interconnections. This transfer capability is not much compared to the size of the networks they connect—the larger Eastern Interconnection has 700,000 MW of generating capacity. But these strategically located interconnection facilities (“seams”) will soon be ready for replacement. They present a timely and impactful opportunity to modernize the U.S. electric grid.