as far as vs though

as far as

conj
  • To the degree or extent that. 

  • Used other than figuratively or idiomatically: see as, far, as. 

prep
  • With respect to; as relates to. 

  • Used other than figuratively or idiomatically: see as, far, as. 

though

conj
  • Despite the fact that; although. 

adv
  • Used to intensify statements or questions; indeed. 

  • Despite that; however. 

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