burb vs township

burb

noun
  • A suburb. 

township

noun
  • A small town. 

  • A nonwhite (usually subeconomic) area attached to a city. 

  • A subdivision of a county. 

  • The territory of a town. 

  • An area set aside for nonwhite occupation. 

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