I grew up in a part of the Eastern US, where most land is private, but state and federal parks are reasonably frequent. BUT, then I moved to Arizona, which has

I grew up in a part of the Eastern US, where most land is private, but state and federal parks are reasonably frequent. BUT, then I moved to Arizona, which has enormous amounts of federal land that is easily accessible. Quite delightful. Unfortunately, the lawsuit happy nature of the US means that you can easily be held liable for anything happening on your land, so it is best to fence it off and post no trespassing signs.