There is a dc line from east of Portland to near LA, the pacific inter-tie. It was built as 2 wires in the 70s, carrying 1.4GW. Since then, over many changes,

There is a dc line from east of Portland to near LA, the pacific inter-tie. It was built as 2 wires in the 70s, carrying 1.4GW. Since then, over many changes, it was upgraded to 3.1GW. that involved equipment changes at both endpoints, but the lines and towers are still the same, 50 years later.