If you are looking for an adventure off the beaten path but still close enough to civilization to feel confident that you won't get lost, try the Twenty Mule Team Trail located in Death Valley, California.
History tells a tale of the famous Twenty Mule Teams that pulled massive wagons hauling borax from the Harmony Borax Works near Furnace Creek to the railhead near Mojave. This was a 165-mile, ten-day trip across primitive roads back when the amenities were scarce and the weather was often deadly.
The teams only ran for six years -- 1883 to 1889 -- but their impact was forever. You can see two of the last remaining wagons in Death Valley in front of the Furnace Creek Ranch and at Harmony Borax Works while you and Fido hike the trail.
To get there, you have to leave the main highway and enter Death Valley National Park. A small sign will warn you of the entrance right before a small dirt and gravel road. Once you find the trail, you will navigate through majestic mountain areas and beautiful rock formations. The exact elevation incline is not known, but there are multiple inclines along the trail loop.
This trail is considered to be one of the most highly recommended detours while you are traveling on Highway 180. You most likely won't hit everything there is to see in one day as you navigate through the mountain areas and explore the cracks and crevasses along the way, but you will definitely have an un-fur-gettable experience!
Although there is no specific street address for the park or the Furnace Creek Visitor Center located next to it, many GPS users have used the street address for the Death Valley Post Office, slightly south of the entrance. Note that dogs are allowed on this trail as long as they're leashed, cleaned up after, and under your control at all times.