Complex sentence: People from the Coconino County line near Stoneman Lake, Apache Maid Ranch etc. and up and down the creek nearly to Camp Verde picked up their mail at the Rimrock Post Office so the former area of Beaver Creek School district generally became known as Rimrock.
Split into simpler sentences: People from the Coconino County line near Stoneman Lake, Apache Maid Ranch etc. and up and down the creek nearly to Camp Verde, picked up their mail at the Rimrock Post Office. The former area of Beaver Creek School district thus generally became known as Rimrock.