The Postman (1997)

http://en.wikipedia.org/wiki/The_Postman_(film)#Plot

"This navigation system was established and instituted shortly after WWI, and were primarily used for the specific purpose of delivering the mail by air from one side of the country to the other. This navigation system for America consisted of giant concrete arrows that pointed the way and kept pilots on track. Several of these concrete monuments are still in existence, and if stumbled across while lost, they should help you decide the shortest and best direction to take to return to civilization."
http://survivalist.com/navigational-arrows-america

http://www.denofgeek.com/movies/18242/looking-back-at-kevin-costners-the-postman