The Bonneville Salt Flats, about an hour west of Salt Lake City (on I-80), are a peculiar natural phenomenon that has earned global fame as the site where land speed records are set. These flats, which occupy roughly 30,000 acres, formed when Lake Bonneville disappeared. This massive, ancient body of water formed during a much cooler and wetter climate. Roughly the size of Lake Michigan, it covered much of northwestern Utah. Roughly 14,000 years ago, an earthen dam on its northern shores burst, sending its water across southern Idaho in a catastrophic flood. Today, the utterly smooth Bonneville Salt Flats stand at the former bottom of that lake. With soils inhospitable to life and a perfectly flat surface, these flats have been the location of world land speed records for more than a century.