Are there any credible estimates of how much of the US National Park System does not have cell phone reception? If so, what do they conclude?

Question

We have found that almost any place that is interesting to hike, and especially backpack, does not have cell phone reception, or at best lousy cell phone reception.

To which I say hallelujah! I do not want to be in touch with the world when I am hiking. I do not want to keep au courant with my e-mail on the trail, or find out what the latest mess is on and near that Hill 21 miles from my house.

I wonder what percentage of good hiking and backpacking territory has lousy or no cell-phone coverage. So that there is a chance that this question can be answered, I ask about coverage in the US National Parks. That is, I am using the National Parks as a proxy for the greater great outdoors. However, if anyone has information that is not confined to the US National Parks, that would be welcome.

Answer 1

I believe what you are looking for can be found here,

Cellular Coverage in National Parks

which has cell phone coverage maps for a number of National Parks in the US. It depends on the park and has no percentages, but its probably the best one can get. I will note that based on my experience in RMNP, there are more areas with coverage than shown.

It does note,

Most cellular coverage in national parks is provided by cell sites outside the borders of each park. Such service is limited by topography and elevation. This means using cell phones along rivers and valley trails may be impossible, while standing in a high location with a great view may provide excellent coverage. Some park lodges and commercial facilities offer Wi-Fi which can also be used for Voice and Text communications. These facilities are provided by park concessionaires and not by the Park Service itself.

Source

Not everybody is happy with this,

In Yosemite, Yellowstone, Mount Rainier and other iconic parks, environmentalists are pressing the National Park Service to slow or halt construction of new cellular towers within park boundaries. They say the NPS is quietly facilitating a digital transformation with little public input or regard to its mission statement — to preserve “unimpaired the natural and cultural resources and values of the National Park System.”

Wire the wilderness? As cell service expands, national parks become the latest digital battlegrounds

I think the bottom line is that you really can't depend on cell service in National Parks for safety and as the coverage can be rather spotty.