There are a fair amount of Harvest Hosts locations, but they vary according to state and are sometimes rather clustered by region.
Just googling Harvest Hosts, there is this map that shows the number of locations in each state.
https://harvesthosts.com/maps/
You have to be a member to access specifics, I suspect in order to prevent non members from taking advantage.
More locations seem to be added all the time, and for the price of the annual fee seem to me to be a great value for a fee free overnight.
Maggie