To go across the country

from The Collaborative International Dictionary of English v.0.48

Across \A*cross"\ (#; 115), prep. [Pref. a- + cross: cf. F. en
   croix. See Cross, n.]
   From side to side; athwart; crosswise, or in a direction
   opposed to the length; quite over; as, a bridge laid across a
   river. --Dryden.
   [1913 Webster]

   {To come across}, to come upon or meet incidentally.
      --Freeman.

   {To go across the country}, to go by a direct course across a
      region without following the roads.
      [1913 Webster]