August: Mail will be delivered to homes and businesses only from Monday through Friday but would still be delivered to post office boxes on Saturdays. Post offices now open on Saturdays would remain open and packages will still be delivered on Saturdays.
1981: Postal Service is required to deliver mail six days a week under congressional mandate
1950: Twice-a-day delivery is cut to once a day
1918: Airmail becomes a mode of delivery
1863: Six-day delivery begins
1860: The Pony Express begins
1775: Benjamin Franklin is appointed the first postmaster general