American vs US'er

American

noun
  • A citizen or inhabitant of the United States of America. 

  • A citizen or inhabitant of British North America. 

  • The dialect of English spoken in and around the contiguous United States of America. 

  • Any inhabitant of the Americas. 

  • American cheese. 

adj
  • Of, from, or pertaining to the Americas. 

  • Of, from, or pertaining to the United States of America, its people, or its culture. 

  • Able to be exercised on any date between its issue and expiry. 

  • Of, from, or pertaining to British North America. 

US'er

noun
  • A citizen of the United States of America. 

How often have the words American and US'er occurred in a corpus of books? (source: Google Ngram Viewer )