The history of Morse code, from telegraph to radio
Morse code began in the United States in the 1830s and 1840s as the code for the electric telegraph that Samuel F. B. Morse developed with Alfred Vail. It went public on 24 May 1844 with the words “What hath God wrought”, was reworked in Europe into the International Morse code, moved from wires to radio and out to sea, and served as the distress system for ships until 1999. Today it lives on mostly in amateur radio, in the identifiers of aviation beacons and in signal lamps at sea.
Here is the longer version, with the stories that are only “often told” marked as such.
The telegraph years: wires, tape and clicks
Samuel Morse (1791 to 1872) was a painter turned inventor. Alfred Vail (1807 to 1859) was his partner, and is usually credited with much of the practical building. Together, through the 1830s and into the 1840s, they built a telegraph that worked on a plain idea: close a circuit with a key and an electromagnet at the far end of the wire pulls; open it and the magnet lets go. A short closing is a dot, a longer one a dash, and a pattern of them is a letter.
How much of the code itself came from Vail rather than Morse is a question historians still argue about. Who invented Morse code? Samuel Morse and Alfred Vail goes through what is known and what is only told.
The telegraph went public on 24 May 1844. Morse, in the Capitol in Washington, sent “What hath God wrought”, a phrase from the Bible (Numbers 23:23) chosen by Annie Ellsworth, to Vail in Baltimore. The full story of that day is in What hath God wrought: the first long-distance telegraph message.
The first receivers were registers. A register marked the dots and dashes on a moving strip of paper tape, and an operator read the tape afterwards. Operators soon found they could read the clicks of the instrument by ear, and on most lines the sounder replaced the register. A sounder has no tape and no tone, only a lever that clicks down when the current flows and up when it stops. The length of a dot or a dash is the time between the two clicks.
From then on, for most operators, Morse was something you heard, not something you read.
One code becomes two
The code that grew out of Morse and Vail’s work is now called American Morse, or the landline or railroad code. It had features that later codes dropped: spaces inside some characters (C, O, R, Y, Z and the ampersand) and extra-long dashes for L and the figure 0. On American lines and railroads it did its job well.
In Europe the code was reworked. The version that grew into International Morse, also called Continental, is usually traced to Friedrich Clemens Gerke’s revision of 1848. The International code has only two element lengths, the dit and the dah, and only one kind of gap inside a character. That regularity is usually given as the reason it won out, first on European lines and later on radio, where a fading signal could easily swallow an awkward pause.
The two codes are compared side by side in American Morse code vs International Morse code.
International Morse is the one standardized today by the ITU in ITU-R M.1677-1, which sets the timing everyone uses: a dit is 1 unit, a dah 3, the gap inside a character 1, between characters 3, and between words 7. The standard still changes now and then. The at sign, .--.-., was added in 2004, a change usually linked to sending email addresses.
Wireless: Morse goes to sea
Radio carried the same dits and dahs through the air instead of along a wire, and for ships that changed everything. A ship out of sight of land had had no way to reach anyone beyond the horizon. Now its wireless operator could.
Ships needed a distress call. The Marconi company’s operators used CQD. At the 1906 International Radiotelegraph Convention in Berlin, SOS was adopted as the distress signal, and it came into force in 1908. SOS is sent as ...---...: one continuous character of nine elements, with no letter gaps, not the three letters S, O and S sent separately. It is usually said to have been chosen because the pattern is easy to send and hard to mistake, and it does not stand for “Save Our Souls” or anything else. That reading came later.
On the night of 14 to 15 April 1912, the Titanic’s wireless operators, Jack Phillips and Harold Bride, sent both CQD and SOS. It was not the first SOS ever sent, whatever some retellings say, but it is the one most people have heard of.
Learning the code, and some famous messages
Radio needed trained operators, and the twentieth century brought the learning methods still used today. In the 1930s Ludwig Koch, a German psychologist, devised what is now called the Koch method: learn every character at full speed from the start, begin with just two characters, and add another when you copy about 90 percent correctly. Farnsworth spacing, which sends characters at full speed but stretches the gaps between them, is usually credited to Donald R. Farnsworth.
Morse also showed it needs no wire and no radio at all. In 1966, Jeremiah Denton, a US Navy pilot held as a prisoner of war, blinked T O R T U R E in Morse during a televised interview. A code built for wires turned out to work with eyelids.
The end of Morse as the distress system at sea
The professional story ends with a date. The Global Maritime Distress and Safety System (GMDSS), which uses satellites and automated radio alerts instead of an operator listening for Morse, was fully in force on 1 February 1999. From then on Morse was no longer the distress system at sea.
Amateur radio followed a few years later, in its own way. The ITU’s World Radiocommunication Conference made a Morse test optional internationally in 2003, and US amateur licenses have not required one since 23 February 2007. Earlier US exams had tested 5, 13 and 20 WPM; from 2000 only the 5 WPM test remained. Other countries set their own rules, so check yours.
Where Morse lives now
Morse lost its jobs and kept its users:
- Amateur radio. On the air, Morse is called CW, for continuous wave. A Morse signal is narrow and simple, and it can often be copied through noise that would bury a voice signal. You need a license to transmit on amateur bands; you do not need one to learn or to practice.
- Aviation. VOR and NDB radio beacons and ILS localizers identify themselves with two or three letters in Morse, and pilots listen to check they are tuned to the right one. Charts print the code next to the beacon.
- At sea. Signal lamps that flash Morse are still in use.
- People learning it for its own sake. With no Morse test for a US amateur license, most who learn it now do so as a skill for the ear and the hand.
Where is Morse code still used today? has more on each.
If you want to hear the code this history produced, Dot & Dash puts a telegraph-style machine on your Mac: a key, a tone and a paper tape that prints each message in dots and dashes, much as the first registers marked theirs. It uses International Morse, timed to the PARIS standard.
The dates at a glance
| When | What happened |
|---|---|
| 1830s and 1840s | Morse and Vail develop the telegraph and its code |
| 24 May 1844 | “What hath God wrought”, Washington to Baltimore |
| 1848 | Gerke’s revision, usually seen as the root of International Morse |
| 1906 | Berlin convention adopts SOS, in force from 1908 |
| 14 to 15 April 1912 | The Titanic sends CQD and SOS |
| 1930s | Ludwig Koch devises the Koch method |
| 1966 | Jeremiah Denton blinks TORTURE on television |
| 1 February 1999 | GMDSS fully in force; Morse ends as the distress system at sea |
| 2003 | The ITU makes a Morse test optional for amateur licenses |
| 2004 | The ITU adds the at sign |
| 23 February 2007 | US amateur licenses stop requiring Morse |
Questions
When was Morse code invented?
In the 1830s and 1840s, as the code for the electric telegraph Samuel Morse developed with Alfred Vail. Its first famous public message was sent on 24 May 1844.
Is the Morse code used today the same as the original?
No. The original grew into what is now called American Morse, which has spaces inside some characters and long dashes for L and 0. The code used on radio and taught today is International Morse, a later revision with only dits, dahs and regular gaps.
Does SOS stand for “Save Our Souls”?
No. SOS was adopted in 1906 as a signal, ...---..., not as an abbreviation, and its pattern is usually said to have been picked because it is easy to send and recognize. “Save Our Souls” is a later reading of the letters, not their origin.
Is Morse code still used?
Yes, though no longer as the distress system at sea. Amateur radio operators use it as CW, aviation beacons identify themselves in it, and ships still flash it with signal lamps.