Source : Webster's Revised Unabridged Dictionary (1913)

Transcontinental \Trans*con`ti*nen"tal\, a. [Pref. trans- +
   continental.]
   Extending or going across a continent; as, a transcontinental
   railroad or journey.

Source : WordNet®

transcontinental
     adj : spanning or crossing or on the farther side of a continent;
           "transcontinental railway"; "transcontinental
           travelers"; "a transcontinental city"