As the crow flies



"As the crow flies" or "in a beeline" is an idiom for the shortest distance between two points (on a map, disregarding the vagaries of intervening terrain); the geodesic distance. A parallel idiom, "as the wolf runs", is sometimes used to indicate the contrasting (and possibly much larger) distance required to travel between the two points over available surface routes.

Resources

 * As the crow flies at Wikipedia