Here's something ya probably didn't know!
Back in the days before radar and modern navigation methods the airmail still had to go through, so the U.S. Mail Service erected a whole bunch of concrete arrows with beacons over them to help guide the mail planes at night! (It was like a more modern version of the railways spreading across the land.)
Here's a map of some of the locations:
And some of the routes:
Here's a typical airmail pilot moonlighting as a crop duster: