If our various sovereign state governments can require those who live in them to adhere to certain decrees, it would seem to me that other sovereign governments within the US can shut down highways through their own land.
I’m not aware that any of the 50 states have done this, but the reservations have unique concerns.
> ...shut down highways through their own land.
I’m not familiar with these particular highways. However in Arizona there are a few going through tribal lands that, if shut down, could add a detour of several hours to your trip.
Federal and state highways through the reservations belong to the taxpayers of that state and to the taxpayers of the United States. Again all ratepayers pay for the electrical power grid. The reservations lacking industrial and commercial entities pay a small proportion of the cost of electrical generation and transit. If they want to build a electrical power station on the reservation fine. If they want to partake in the infrastructure of the rest of the state then they must be partners and not close off access to the reservation. Can’t have it both ways.