boardwalk vs prom

boardwalk

noun
  • A slightly elevated path for pedestrians over sandy or swampy ground, typically made out of wood; specifically (Canada, US) one running alongside a body of water or beach. 

verb
  • To install a boardwalk over. 

prom

noun
  • A promenade. 

  • A formal ball held at a high school or college on special occasions; e.g,. near the end of the academic year. 

  • A promenade concert. 

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