Thanks to compdude for pointing out this discussion. As he mentioned, I've been working hard in Washington state, but there is still so much left to do. It's nice to see the map above:
But, in this view of the map there are several wind farms that aren't shown, and I believe a couple dams (power_source=hydro) that aren't shown either.
I think one of the main stumbling blocks I've had is visualization, so that I can see where I need to work still.
Does anyone have any suggestions on usable sources for line voltage?