When William Penn granted most of this area to Welsh settlers, Planebrook was an important stage-coach stop at the intersection of State highway 29 and Swedesford Road in East Whiteland Township. It was originally called White Horse for a tavern dating to 1721. It was renamed Planebrook when a post office was established there in 1898. Ann M. Clark was the first postmaster. There was an unnamed brook passing by the village which suggested the name Planebrook to her.