They are all quite accessible via roads, but there are places in SE Oregon and northern Nevada that are very far from anything. ~2 hours to get to a town with a supermarket and medical center.

Alaska has lots of places that are only reachable by air or by extremely difficult overland routes that may only be passable during certain times of year.

Supai, Arizona [0] is only accessible by helicopter or an 8-mile hike from the nearest road.

[0] https://en.wikipedia.org/wiki/Supai,_Arizona

And it's worth every bit of the journey to see the waterfalls.

https://fernweh.photo/2016/11/19/supai-arizona/

The helicopter "pad" and the hiking trailhead are themselves many miles from the nearest town. Supai is often claimed to be the most remote town in the 48 contiguous states.

Even whole regions of the world like Zomia function without national governance. https://en.m.wikipedia.org/wiki/Southeast_Asian_Massif#Zomia