After 13 miles, I reach the little dirt road to Indian Springs and turn off here

The road will dead-end at Indian Springs, some 3.5 miles away. There are no signs at most intersections (except the major ones) in Mojave National Preserve; you simply need to know where your chosen road is.

I like this design approach because it keeps the discovery level high for those of us who value that. On my first trip out here, I didn't even notice this road when I passed it.