If you’ve traveled across America, you might have come across a giant concrete arrow. Likely it’s brush covered and a little rough.

If you’ve ever wondered what they’re for – they’re actually for pilots. Before modern air traffic control, cross country pilots relied on landmarks…and the arrows were built to guide them. Specifically, they pointed in the direction of the next beacon…part of a network of lighted beacons that were built by the Post Office.

This was one of the first examples of air traffic control. Let’s look a bit more at the history.