expressway vs interstate

expressway

noun
  • A road built to freeway standards. 

  • A divided highway, especially one whose intersections and direct access to adjacent properties have been eliminated. 

  • A road built for high speed traffic, but not up to motorway standards or designated a motorway. 

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). 

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