You probably know your mail carrier and the clerks at your neighborhood Post Office, but how well do you know the Postal Service itself? Here are nine facts that might surprise you.

9. The phrase by Herodotus etched atop the James A. Farley Building in Manhattan — “Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds” — isn’t the official Postal Service motto. We don’t have a motto.

8. The Postal Service is environmentally friendly. Examples: We’ve cut energy consumption in our facilities by more than 30 percent during the past decade, and we’ve made it easier for federal agencies to recycle old electronics through the mail.

7. We’re the only organization that delivers to every residential and business address in the nation.

6. The Postal Service has the country’s largest retail network. In fact, it’s larger than McDonald’s, Starbucks and Walmart combined, domestically.

5. We compete with the private sector, and we collaborate with it too. UPS and FedEx pay the Postal Service to deliver more than 470 million of their ground packages to residences, taking advantage of our expansive delivery network. We pay UPS and FedEx for air transportation, taking advantage of their comprehensive air networks.

4. Mail is a great communication tool. No monthly plans. No signal outages. No roaming charges. Regardless of geographic location, anyone can send a letter for just 49 cents to anywhere in the nation.

3. Mail is reliable, trusted and secure — more than 200 federal laws protect the sanctity of the U.S. Mail. These laws are enforced by the U.S. Postal Inspection Service, one of the nation’s oldest law enforcement agencies.

2. The Postal Service continues to improve customer service by increasing access to postal services online, on smartphones and in the places people visit every day, including grocery stores, drug stores, other retailers and ATMs.

1. The Postal Service receives no tax dollars for operating expenses and relies on the sale of postage, products and services to fund its operations.

Which of these facts surprised you most? Share your thoughts in the comments section below.