Lost Horse Mountain is the high point of the Lost Horse Mountains, a small range in central Joshua Tree National Park. It derives its name from the Lost Horse Mine, which you will encounter on the standard route. The mine was owned by Pioneer Johnny Lang, who got the last laugh on a gang of horse thieves who had stolen his horse, and generally given the locals a bad time. After purchasing the rights to the mine, Lang's gold prospect earned him up to $3,000 per day--much more lucrative than stealing horses!
A road formerly used to supply the Lost Horse and other nearby mines is now the standard route to the top. It is a scenic 5 mile round trip, with only 900 feet of gain. From the parking area at the end of the Lost Horse Mine Road, pass the gate and walk about two miles to the Lost Horse Mine. Continue past the mine a short distance to a saddle south of the mine, and then head up and right on use trails to the summit. Return the way you came.
From the Town of Joshua Tree, head into the Park. Just before Ryan Campground, and just after Hidden Valley CG you will encounter the Keyes View Road on the right. Turn here, and go about 2.5 miles to the Lost Horse Mine Road on your left. Turn here and follow the good dirt road about a mile to a small parking area. The hike starts here.
Lost Horse Mountain is in Joshua Tree National Park. Entrance fees will vary depending on you age, vehicle, and whether you own any or a variety of passes. A single vehicle pass good for seven days costs $15. Dogs are not permitted beyond 100 feet from paved roads, so if you're inclined to bring your pooch, you could get a ticket.
The nearest campgrounds are Hidden Valley and Ryan campgrounds. A little further east is the Sheeps Pass Group Campground. Fees for Ryan and Hidden Valley are $10/night, no reservations allowed--it's first come, first served. Sheeps Pass is $15/night, and can be reserved. See the NPS web site for more details.