From Bouvier's Law Dictionary, Revised 6th Ed (1856) :
PORTER. The name of an ancient English officer who bore or carried a rod
before the justices. The door-keeper of the English parliament also bears
this name.
2. One who is employed as a common carrier to carry goods from one
place to another in the same town, is also called a porter. Such person is
in general answerable as a common carrier. Story, Bailm. Sec. 496.