Bonneville Salt Flats

The flats are the bed of Lake Bonneville, a Pleistocene lake far larger than the Great Salt Lake, and when it evaporated it left a salt crust covering around 120 square kilometres - hard, level and reflective, with a curvature-visible horizon. Speed trials have run since the 1910s and the Bonneville Speed Week each August is the main event, with several land speed records set here. The crust is getting thinner: measurements show substantial loss over decades, attributed to a combination of potash mining brine extraction nearby, groundwater changes and flooding patterns, and restoration pumping has been tried. In winter and spring a shallow layer of water covers the flats and turns them into a mirror, which is the photograph most people want.

What you'll find

• A salt crust over 120 square kilometres - hard, level and blinding white.
• Speed trials since the 1910s - Speed Week each August.
• A crust measurably thinning - from mining, water and flooding changes.
• A mirror in wet season - shallow water over the whole surface.

When to go

July to September for dry crust; winter and spring for the mirror effect. Half a day.

Good to know

Driving on the flats when wet sinks vehicles and salt destroys undercarriages - rinse thoroughly afterwards. There is no shade or water. Glare requires sunglasses and burns skin from below. Racing events close public access.

Nearby

Wendover is west on the Nevada line; the Great Salt Lake is east.

Key facts