cover ground vs travel

cover ground

verb
  • To do a certain amount of work; to make progress towards an end. 

travel

verb
  • To force to journey. 

  • To move illegally by walking or running without dribbling the ball. 

  • To travel throughout (a place). 

  • To pass from one place to another; to move or transmit 

  • To be on a journey, often for pleasure or business and with luggage; to go from one place to another. 

noun
  • An account of one's travels. 

  • The working motion of a piece of machinery; the length of a mechanical stroke. 

  • The activity or traffic along a route or through a given point. 

  • Distance that a keyboard's key moves vertically when depressed. 

  • The act of traveling; passage from place to place. 

  • A series of journeys. 

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