When was Eastside’s electric system built, and why was it not built as a 230 kV line?

The Eastside’s electric transmission system was built in the 1930s and upgraded in the 1960s to 115 kV – the last upgrade to the electric transmission system was sufficient to meet the power needs of Eastside communities for the last 50+ years. However, the Eastside is now growing faster than any other region in Washington and this growth is straining the existing transmission system.