Here’s what the Eastern Interconnect looks like, extending into tiny parts of Wyoming and Texas. Small pie charts resting on the lines indicate what percent of total capacity the lines are carrying. Lines carrying over 60% are flagged with blown-up pie charts (Note that some lines near NYC are carrying over 100% of capacity… but the page doesn’t seem to update).
And here are the specs for a high-voltage circuit breaker. I guess it’s not so easy to route huge surges into the ground without melting down key equipment…