Almost every place where people live and work is covered. I would venture to guess that less than 100,000 people in the whole USA outside of Alaska live in places that are not covered by Verizon. Yeah maybe you'll find a town here and there of a few hundred people in a very remote area that is not covered. Similarly I bet the vast majority of the USA is reached by at least one line of sight FM radio station.
For specific examples of areas that are not covered on the map: north west maine. Nobody lives there. There are no incorporated towns north or west of Rangley or south or west of Alagash. It is private forestry company land.
Death Valley.
A part of east texas near the LA border. I am not too familiar with this area but I believe it is part of the area called the "Big Thicket" it is very sparsely populated.
The Nevada test site, Nellis AFB, Area 51. I am sure the military has its own radio coverage here where it needs it.
Other Parts of Nevada and Eastern Oregon and Washington and North Central Idaho. These areas are sparsely inhabited deserts or mountains.
This seems like a city-centric view of things. You get Verizon near highways just about everywhere around here, but 1 mile from the highway at my house I get spotty Verizon on one side of my house (enough to use voice on phone, not enough to reliably use a hotspot device), and pretty much nothing on the other side. Verizon coverage map claims to cover everything within hundred miles perfectly with LTE, reality is moving 100 feet can change whether you can get a signal or not.
If your house is made of radio opaque materials that maybe most of your problem. Brick, stone, concrete all seriously attenuate some radio frequencies. Metal roofing or solar pannels on the roof or foil backing insulation would also contribute to signal attenuation.
For specific examples of areas that are not covered on the map: north west maine. Nobody lives there. There are no incorporated towns north or west of Rangley or south or west of Alagash. It is private forestry company land.
Death Valley.
A part of east texas near the LA border. I am not too familiar with this area but I believe it is part of the area called the "Big Thicket" it is very sparsely populated.
The Nevada test site, Nellis AFB, Area 51. I am sure the military has its own radio coverage here where it needs it.
Other Parts of Nevada and Eastern Oregon and Washington and North Central Idaho. These areas are sparsely inhabited deserts or mountains.