[technothrasher]

This depends upon the state. Here in MA, you cannot stop people from being on your 'unimproved land'. In other words, people are not allowed to trample your lawn, but they are free to wander your woods. There are generally town bylaws against hunting land without the owner's permission though.

[jpindar]

In NH, landowners get a significant discount on their property tax if they allow hiking, fishing etc. on their unimproved land.