Before the Delaware State Police was formed in 1923, the first traffic law enforcement officers were called the "Highway Traffic Police". Started in 1919, the HTP consisted of one officer whose sole function was to patrol the Philadelphia Pike near Wilmington. In the following year the force was increased to three men and three motorcycles. From 1920 to 1923 these men served directly under the State Highway Commission. Prior to the formation of state police the areas between unincorporated districts were served by the county sheriff department.