Thank you for the info. It appears to be in the 7% range of loss during transmission, with much more occurring at the plant.
The article I read in the 70s was a Popular Science article, I believe, and they used a 50% loss for transmission, but they might have included the losses during the generation as well.
Glad to help. A transmission line with large loss like 50% would have many other problems such as voltage drop, line heating and associated drooping conductors.