In general anywhere in the USA that is "on" an Interstate is solved problem for EVs. If you want to drive on I-whatever you're covered. The question above was about getting to remote areas far from infrastructure. And even there you need to work really hard to be far from a wall outlet.
Again, incremental costs to build out (non-supercharger) vehicle charging is much cheaper than installing a gas station, because it's ultimately just freeloading on the long-established electrical infrastructure.