I'm sure it is everywhere. I'm in NW Montana and was recently checking out coverage maps of various carriers. I had never noticed the fine print telling me something like "coverage" was defined as slow and would only work outdoors. If I'm in my house, I'm lucky to get a signal on one side of it.

I really do count it as lucky. My neighbor doesn't get anything at all - inside or out, but the coverage map says he's good. A few years ago, before buying a phone, he borrowed a Verizon phone (from them) to make sure it worked at home. It did, he bought it and a few months later it quit working. The phone is fine, I guess they are no longer using the tower that served him. I don't think they updated their coverage map.