What is “snail mail” and how does it travel?

The term “snail mail” is used for regular mail that is sent through the United States Postal Service. Once you address a letter, affix postage stamps, and drop it in the mailbox, a complex process begins that requires the efforts of many people and machines—sometimes located in different parts of the world. Mail carriers visit mailboxes in your town or city a few times each day to pick up their contents. The mail collected by carriers is taken to a local postal sorting office, where it joins all the other letters that have been mailed in the area that day. High-speed machines take over then, preparing your letter to reach its destination. Mail is dumped onto a moving conveyor belt that brings it to a machine that separates it by size. Another machine checks to make sure that all the mail is properly stamped, and then it cancels, or prints over, the stamps so that they cannot be used again. A postmark is also printed on each envelope, which tells the time, date, and place where it was processed. A machine reads the zip codes written in the addresses of letters, which tell exactly to which part of the country, or the world, they are headed. (Postal services around the globe work together to distribute mail and most have similar code systems.) Postal workers process by hand the letters that have missing or unreadable zip codes. The zip code machine prints a bar code (a machine-readable series of lines, more reliable than written numerals) on each letter, and a second sorting machine reads and separates them by destination. Mail is grouped by city and country. Local mail is prepared for delivery the next day. Other mail travels by truck, express train, or plane, depending on where it is going. Each delivery day, the Postal Service sorts and delivers more than 700 million pieces of mail. Because of this complex process, and that it takes longer to reach its destination than email, it is referred to as snail, or slow, mail.