If you look out the window as you fly over Kansas, you will not see the neat, rectangular grid that aerial photography has trained you to expect. In fact, you’ll see something that looks a whole lot like crop circles.
NASA and the U.S. Geological Survey recently took a look at Garden City, Kans., training Landsat satellites on fields of corn, wheat, and sorghum. Their images show how dramatically the shape of American farming has changed over the past few decades.
Sixty years ago, farmers mostly relied on the rain to sustain their crops. But then, a new technology called center-pivot irrigation came along. It pumps groundwater from a well and then waters the fields through a long pipe that rotates around the well. This method creates circular fields, since the irrigation system can only move in that shape.
While center-pivot irrigation was only used by a few farms in the 1970s, by 2011, it had become the default, as you can see in this GIF of aerial images from 1972 to 2015:
Image Credit: NASA's Goddard Space Flight Center
It looks kind of like a dorm-room rug.