The ARRL National Traffic System (NTS) is a well-organized system for routing formal written message traffic (radiograms) from any point in the United States to any other. Messages are relayed from one ham to the next, using a variety of modes such as voice, Morse code, radio teletype, or packet radio. The NTS has it origins in the earliest days of radio as is indicated by the name, "American Radio Relay League" itself.
In times of emergency, radiograms may be used to communicate information critical to saving lives or property or to inquire or learn about the health or welfare of a disaster victim. During these times, NTS works in concert with the Amateur Radio Emergency Service (ARES) and other emergency and disaster relief organizations.
However, the NTS does not operate only during disasters. It operates day in and out 7 days a week, 365 days a year and is used by thousands of people, hams and non-hams, to send and receive brief greeting messages (happy birthday, congratulations on the arrival of a new baby, hope you feel better, etc.) as long as they are of a personal, non-commercial nature (as defined in the FCCrules).
Subject to international treaties governing "third party" messages, many foreign countries also allow their hams to exchange radiograms with US hams.
Within the Westchester and Rockland County area, our local NTS net is the Southern District Net, which meets at 9:30PM each evening on WB2ZII/R, 147.060 MHz.
Non-hams wishing to avail themselves of the NTS are encouraged to contact a local ham friend or neighbor (look in our roster).. There's no charge to send a radiogram. It's one of the ways ham radio serves the public interest. (In case you are wondering, sending grandma a birthday greeting provides ham traffic handlers with practice for emergency communications. And, it's fun!)
More information about the NTS can be found in the ARRL Public Service Communications Manual.