interstate vs roadway

interstate

noun
  • A freeway that is part of the Interstate Highway System. 

adj
  • Of, or relating to two or more states. 

adv
  • Crossing states (usually provincial state, but also e.g. multinational sense). 

roadway

noun
  • The portion of a bridge or railway used by traffic. 

  • The main or central portion of a road, used by the vehicles. 

  • A way used as a road. 

How often have the words interstate and roadway occurred in a corpus of books? (source: Google Ngram Viewer )