Tri-State is one of the few utilities that supplies electricity on both sides of the national electric system separation. Since 1977, the G&T has owned and operated the David A. Hamil DC Tie at Stegall, Neb., which joins the eastern and western power grids. It was the first such facility built in the United States.
Direct current (DC) ties bridge the national electric separation between the eastern and western power grids by converting alternating current to direct current, and then converting it back to alternating current. That conversion is necessary so that the energy is in sync with the alternating current on the other side of the system separation.