Bonneville Salt Flats

West of the Great Salt Lake, where Utah meets Nevada, the desert floor turns into a sheet of white so flat that the curvature of the Earth seems visible on the horizon. The Bonneville Salt Flats run about 19 kilometres long and 8 wide, a hard crust of salt — almost entirely common salt — that is about a metre and a half thick at the centre and thins to a couple of centimetres at its edges. Mountains rise around the margins, and the light changes the plain from hour to hour.

The flats are what is left of Lake Bonneville, a vast lake that covered much of the region during the Pleistocene. The geologist Grove Karl Gilbert named it after Benjamin Bonneville, the US Army officer who explored the area in the 1830s. As the lake dried, its dissolved salts were left behind — an estimated 147 million tons of them — forming the smooth crust that makes the place unique.

That smoothness made Bonneville the home of speed. Racing began in 1914, when Teddy Tetzlaff set the first record here, and over the following century cars and motorcycles chased land speed records across the salt — the fastest wheel-driven run reached about 449 miles per hour in 2018, and a rocket-powered car topped 630 miles per hour in 1970. Speed Week each August, followed by further events into the autumn, still draws racers when the salt is firm. The crust has been thinning, with nearby potash mining suspected as a major cause, and since 1998 brine has been returned to the flats in winter to help rebuild it.

The salt is at its most magical after the winter rains. From about January to March a thin film of water often lies over the flats, turning them into an enormous mirror in which sky, clouds and mountains are doubled. In summer the dry crust is blinding white and crunches underfoot.

Getting there

The flats sit along Interstate 80 just east of Wendover, on the Utah–Nevada line; exit 4, signed Bonneville Speedway, leads to the racing area, and there is a rest area on the south side of the interstate. Tooele is about 130 km to the east, and Salt Lake City further east along I-80 is the main gateway. The nearest airport by straight line is Joslin Field – Magic Valley Regional Airport (TWF) at Twin Falls, Idaho, about 195 km away. The land is public and administered by the Bureau of Land Management; drive onto the salt only when it is dry and firm — wet crust traps vehicles.