cross the line vs overstep the mark

cross the line

verb
  • To overstep a boundary, rule, or limit; to go too far or do something unacceptable. 

  • To achieve completion of something. 

  • To finish a race. 

  • To cross the equator, as a vessel at sea. 

  • To film from the opposite side of an imaginary axis on set in order to view the actors from the opposite direction. 

overstep the mark

verb
  • To behave in an unacceptable or morally reprehensible way. 

How often have the words cross the line and overstep the mark occurred in a corpus of books? (source: Google Ngram Viewer )