In 1746, the inhabitants of the settlement petitioned for Township status with the result that Mount Bethel Township was established in 1748. It included the present-day Townships of Upper Mount Bethel, Lower Mount Bethel and Washington. Development at that time was concentrated in the areas near Martins Creek and Richmond.
One of the early landmarks of the region was Bethel Church built in the 1740's one mile north of Martins Creek. The church was the home of David Brainerd, one of the most outstanding Indian Missionaries in the colonies at that time. Brainerd began his missionary work in 1744 and died in 1747. Two historic markers are at the site of his home and mission.
During the mid-eighteenth century, a large number of Germans settled in the Mount Bethel region. In a short time, a conflict arose between the Scotch-Irish and Germans, resulting in the persecution of the Scotch-Irish minority. Shortly after the end of the Revolutionary War, a number of the Scotch-Irish families living in Mount Bethel Township moved to central and western Pennsylvania and to Tennessee. This event, coupled with more German immigration, created a dominant Germanic influence in the Township.
In 1787, Mount Bethel was divided into two parts - Lower Mount Bethel Township and Upper Mount Bethel Township. At that time, the area of Lower Mount Bethel included present-day Washington Township