2021 Grand Canyon Calendar! The Grand Canyon is 18 miles wide and 277 miles long. At its deepest, it reaches a depth of over a mile! Geologists estimate that it took 6 million years for the Colorado River to carve this behemoth into the land that is now Arizona. Take one look at these stunning images, and you will be left with no doubt that its size is matched by its beauty. Enjoy this beautiful destination wall calendar.