Ask Kasey Cottam, he always left the mission boundaries.
J/K
From what I remember, the boundaries westward were the Chesapeake bay, (no swimming) southward was the suitland stake, and anarundal county. Eastward not sure, don't leave Maryland in this direction unless you intend to keep on going home. Northward follows the state boundaries except for one small section of harford ward which goes into Penn state. (the state not the university.