The US doesn't have a nationwide grid because of the technical requirement to use AC back when electrification happened (which requires phase matching or DC int

The US doesn't have a nationwide grid because of the technical requirement to use AC back when electrification happened (which requires phase matching or DC intertie between subregions), and because of the politics of who regulates the grid (which is why Texas still has its own grid.) The AC requirement is a legacy historical issue; a nationwide DC grid could be built in the US tomorrow if the political issues could be solved (and if it made economic sense to rip out the legacy AC infrastructure, which it doesn't.)