Concrete Arrows Guided Early Airmail Pilots Across The Country.
http://www.atlasobscura.com/articles/the-pilots-who-risked-their-lives-to-deliver-the-mail?utm_source=Boomtrain&utm_medium=email&utm_campaign=20160620&bt_email=prigger69@gmail.com&bt_ts=1466433335834
"I regard my Paris flight as no more dangerous than flying the U.S. Mail during one winter." - Charles Lindbergh
