That's not entirely true. There are no CCS DC fast chargers (the type the bolt uses) in much of Idaho, Montana, Wyoming, and North/South Dakota. You might be able to drive from Seattle to NYC but you'd have to drive pretty far out of your way to do it.
Super chargers are available in all of those states, making any cross country driving in that area significantly faster and easier.
"Can't go" is probably the wrong term, but rather it's not very practical without a Tesla. "fast-charging" just isn't that fast in the US for non-tesla setups. 50kW max (which you don't normally get, usually it's something less) requires you to stop for at least an hour every 2-3 hours in a Bolt.
Add in winter conditions and driving at the usual ~75MPH and it gets worse than that. I wouldn't attempt any trip longer than ~200 miles in anything but a Tesla because even the superchargers at 130kW make it just ~bearable once the supercharger novelty wears off.
This just isn't true, check plugshare.com. It is now possible to drive cross-country in any EV with fast charging.