Fall Rock post office was established on 1924-05-22 by postmaster John Campbell, and named after the original name of Morgan Branch which was Falls Branch or Fall Rock Branch.[4]
This in turn came from the name of the 10 feet (3.0 m) high waterfall that powered a local grist mill and was also used for social events.[4]
However, the village and school were originally named Pinhook, local oral histories stating that this was after a local fisherman who made fishing hooks out of safety pins bought in the local store.[4]
Named John Campbell (not the aforementioned postmaster) he gained the name "Pinhook" Campbell.[4]
The village and school were renamed after the post office when schooling was consolidated in the county in the 20th century.[4]
