Answer:
They mapped trails and built forts.
Step-by-step explanation:
The mountain men and trappers prepared the west for settlement by mapping trails and building forts.
The Mountain men played a very important role in western settlement because they helped to make out some of the east-to-west routes that the wagon trains passed through.
The Mormon Trail, California Trail, Oregon Trail and Santa Fe Trail were trails used by Americans as they moved from East to west.