Typically the amount of air space is assumed to be to the height of a typical two story house. This is why some people have been forced to remove private wind generators and flagpoles from their property, those things stood higher than the typical two story house and as such exceeded their private property boundaries.
I'm not being testy, but "typically"...is that law or neighborhood covenants? Covenants aren't law. Who forced who to remove a private wind generator? Is there case law on that and something to refer to, a link? I'd like to see if that's something that really happens. I have a neighbor, in fact many neighbors, with trees way higher than two story homes, and a three story home. Also grain elevators on commercial land. Two story home with daylight basement, etc. A link to where someone was "forced to remove" that wasn't due to covenants would be nice.
I'd never trust a GPS to tell me where a corner is. Only a surveyor's stake. Period.
My point above, if there is no law that states height of private land "air" boundary, is "precedence": If the air above is private, how high does it go? Honestly? If there's no limit and the land owner has never gone after commercial aircraft, private aircraft, etc., why pick on someone who steps over a known corner? I know this sound ridiculous: an aircraft at 30,000+ feet! However, if there is no legal reference to the privacy of the air above ground or known elevation limit, no past legal rulings, does a person stand a chance by referencing every other form of human that has trespassed in the air above?
I don't cross corners but wish there was a legal ruling. If there's no legal air space above private ground, we'd win.
The amount of public land that's not accessible, but could be with corner crossings, is massive.