I've thought the same thing and then realized the impossibility of it. The reason being, in most western states, there are tens of thousands of patented mining

I've thought the same thing and then realized the impossibility of it. The reason being, in most western states, there are tens of thousands of patented mining claims. When a claim gets patented, it is private property, including both mineral and surface rights. Lode claims, the most common, are 10.66 acres. I was trying to find the boundaries of a lode claim, knowing which quarter (160 ac) it was in. I ended up finding an old mineral survey marker for one corner of the claim and nothing else. So making an app that lets hikers skirt around private property is going to be quite imperfect unless things are resurveyed with modern technology, a huge and expensive undertaking.