Line 9" pie pan with pastry.
Combine sugar, flour, cinnamon and salt.
Mix in apples.
Fill pastry with apple mixture.
Cut butter into thin slices and lay on top of of apples.
Top with pastry, trim and seal edges.
Cut a few slits in top of crust to let steam escape.
Sprinkle with additional sugar and cinnamon if desired.
Bake at 400 degrees for 50-60 minutes, or until apples are done.