Combine sugar, flour, salt and cinnamon. Stir into liquid drained from berries. Heat, stirring constantly until thick and smooth. Add berries and butter, mixing gently, pour into an unbaked pastry shell and cover with top crust. One teaspoon lemon juice may be added if desired. Bake in at 400°F for 30 minutes, or until well browned. Makes one 8-inch pie.