18 U.S. Code § 1857 - Fences destroyed; livestock entering
Whoever knowingly and unlawfully breaks, opens, or destroys any gate, fence, hedge, or wall inclosing any lands of the United States reserved or purchased for any public use; or
Whoever drives any cattle, horses, hogs, or other livestock upon any such lands for the purposes of destroying the grass or trees on said lands, or where they may destroy the said grass or trees; or
Whoever knowingly permits his cattle, horses, hogs, or other livestock to enter through any such inclosure upon any such lands of the United States, where such cattle, horses, hogs, or other livestock may or can destroy the grass or trees or other property of the United States on the said lands—
Shall be fined under this title or imprisoned not more than one year, or both.
This section shall not apply to unreserved public lands.