The United States Postal Service recently came out with some interesting numbers on their services and while you're dropping a lt'etter in the mail or picking up some shipping supplies. It's worth noting that the USPS processes a total of over 175 billion pieces of mail each year with over half a billion pieces of mail processed each day. Amazingly, the United States accounts for forty percent of all mail volume in the world each year from over 36,000 postal outlets across the United States. Although the internet has certainly put a dent in sales, total mail volume is still significant.