Jeannette Cooperman in The Common Reader:
In the twenties, Archie League was spinning, diving, and doing loop-the-loops above the clouds, engine roaring, little plane shaking as he and the other barnstormers in his flying circus entertained folks across Missouri and Illinois. Necks grew stiff from watching, eyes squinted against the light, jaws dropped and air rushing in with every oooohhhh and whoa and oh my sweet Lord Jesus.
By 1929, though, League had crossed over to safety’s side and taken a job with St. Louis’s nine-year-old airport. Every day, he walked to the end of the Lambert Field runway with a wheelbarrow that held a deck chair, a beach umbrella for summer heat, a notepad, his lunch and, most important, two flags. The big red one meant STOP, and the checkered one meant GO, you can take off or land now.
He was, in other words, the first air traffic controller.