A double-circuit 230-kv transmission line from the Garrison Dam power plant to Bismarck, N. Dak., and a singlecircuit 230-kv transmission line from Bismarck to Jamestown, N. Dak., were recently constructed by the Bureau of Reclamation as a part of the proposed ultimate system to transmit power from the Federal power plants on the Missouri River to wholesale customers in the Missouri River Basin. The lines are designed for National Electrical Safety Code heavy-loading conditions with additional vertical strength in the crossarms to support the conductors with 1?-inch radial thickness of ice. The conductors used on both circuits of the Garrison-Bismarck line are 795,000-circular-mil (CM) steel-reinforced aluminum cable (ACSR), 26 Al/7 st. The conductors on the Bismarck-Jamestown line are 954,000-CM ACSR, 54 Al/7 st. Two 1/2-inch high-strength-grade 7-wire class-A galvanized steel-strand overhead ground wires are used for the full length of each line. The design features of these transmission lines are typical of Bureau of Reclamation lines constructed since 1946.