The Old Mojave Road was first used by Native Americans, later Spaniards, and then early American settlers to make their way west through the perilous Mojave Desert. The trail cuts through what is now the Mojave National Preserve and has become a famous trek for off-road enthusiasts.
Near mile 100 of the road, on the dry Soda Lake (and just south of Zzyzx) can be found Travelers Monument, a large and seemingly random pile of rocks (and California state flag) in the middle of the road. The tradition states that travelers should carry the largest rock they can across Soda Lake to deposit on the monument for good luck, and as a memento of their visit to this far-flung place.
The origins of the monument are unclear, but travelers have been adding their rocks (some painted, stickered, or with messages) to the pile for decades. Near the top of the pile, among the rocks, there is even a plaque with a supposed-to-be secret message—so you will have the visit the monument to see what it says.