I'm interested in the history of the 345 kV power level for high voltage transmission in the United States. I've got two (and a half) questions:
According to this source 345 kV was first applied in 1953 by American Electric Power. Who has developed it and why have they chosen exactly this voltage? Because it is 3*115 kV and nearly 2*161 kV?
When you look on this power network map you will notice, that 345 kV is still the most highest voltage for the transmission networks of the Midwest and Texas. Why does they still stick to 345 kV even for new-built power lines despite 500 kV would be much more economic (less losses at a similar right-of-way width)?
PS: I've thought that "Engineering" wouldn't be the right category for this question, but I was advised so at Meta.