20 Mule Team Canyon Trail, Death Valley, California

Driving in our high clearance, all wheel drive vehicle, this road was fun to drive. It is actually passable by almost all passenger cars. This is part of the road used to access the borax mined by those who shipped their tons of minerals in huge wagons pulled by 18 mules and two horses. Despite the horses, they were called 20 mule team wagons. Here is a description of the wagons from Wikipedia.

In 1877, six years before twenty-mule teams had been introduced into Death Valley, Scientific American reported that Francis Marion Smith and his brother had shipped their company's borax in a 30-ton load using two large wagons, with a third wagon for food and water, drawn by a 24-mule team over a 160-mile stretch of desert between Teel's Marsh and Wadsworth, Nevada. 

The twenty-mule-team wagons were designed to carry 10 short tons (9 metric tons) of borax ore at a time. The rear wheels measured seven feet (2.1 m) high, with tires made of one-inch-thick (25 mm) iron. The wagon beds measured 16 feet long and were 6 feet deep (4.9 m long, 1.8 m deep); constructed of solid oak, they weighed 7,800 pounds (3,500 kg) empty; when loaded with ore, the total weight of the mule train was 73,200 pounds (33.2 metric tons or 36.6 short tons). 

The first wagon was the trailer, the second was "the tender" or the "back action", and the tank wagon brought up the rear. 

With the mules, the caravan stretched over 180 feet (55 m). No wagon ever broke down in transit on the desert due to their construction.

I remember this most because of the 452 television episodes of the program, Death Valley Days.