If you have ever looked at an old telegraph manual and found letters that do not match the chart you learned from, you have met American Morse code. It is not a mistake and it is not a regional accent: it is a different code, older than the International Morse used today, and for most of the 19th century it was the one that mattered in North America. This article explains where the two systems came from, exactly how they differ, and which one you should bother learning (spoiler: international — it is the one every Morse translator and chart, including ours, uses).
Two codes, one name
American Morse — also called railroad Morse or landline Morse — is the code Samuel Morse and Alfred Vail devised in the late 1830s for their electric telegraph. It was designed to be read from a paper tape and then, as operators learned to copy by ear, from the clicks of a sounder.
International Morse grew out of Friedrich Gerke’s 1848 simplification of the American code for use on German lines. It was standardised in Europe in the 1850s and 1860s and later adopted worldwide for radio. When people say “Morse code” today, this is what they mean. Its history is told in The History of Morse Code.
The structural difference
International Morse has a strict, regular structure: only two elements (the dit and the dah, with the dah exactly three dits long) and fixed gaps (one dit within a character, three between characters, seven between words). Every character is a simple string of dits and dahs.
American Morse is messier. Besides the dot and the ordinary dash, it has:
- an extra-long dash (about four units) used for the letter L, and an even longer one (about five) for the digit 0;
- internal spaces within some characters — C, O, R, Y, Z and the ampersand contain a slightly longer gap between their dots, so that C is “dot, pause, dot dot” rather than “dah-di-dah-dit”.
Those internal spaces were easy to hear on a clicking sounder in a quiet office, but they were a nightmare over a noisy radio link or a long undersea cable, where a moment of static could turn one letter into two. That, in a sentence, is why the international version won.
Which letters are different?
Roughly half the alphabet and most of the digits differ. The table shows the ones that changed (the letters A, B, D, E, G, H, I, K, M, N, S, T, U, V and W are the same in both).
| Character | International | American |
|---|---|---|
| C | −·−· | ·· · (internal space) |
| F | ··−· | ·−· |
| J | ·−−− | −·−· |
| L | ·−·· | ▬ (long dash) |
| O | −−− | · · (internal space) |
| P | ·−−· | ····· |
| Q | −−·− | ··−· |
| R | ·−· | · ·· (internal space) |
| X | −··− | ·−·· |
| Y | −·−− | ·· ·· (internal space) |
| Z | −−·· | ··· · (internal space) |
| 1 | ·−−−− | ·−−· |
| 2 | ··−−− | ··−·· |
| 3 | ···−− | ···−· |
| 4 | ····− | ····− |
| 5 | ····· | −−− |
| 6 | −···· | ······ |
| 7 | −−··· | −−·· |
| 8 | −−−·· | −···· |
| 9 | −−−−· | −··− |
| 0 | −−−−− | ▬ (extra-long dash) |
Notice how tidy the international digits are — every one exactly five signals, following a single rule — compared with the American set, which varies from three to six elements and uses the same sequence for two different purposes (·−·· is L in International but X in American).
Why International Morse won
Three things settled it:
- Radio. From Marconi onwards, wireless operators needed a code that survived fading and static. International Morse, with no internal spaces and a fixed dah length, was simply more robust — and the 1906 Berlin convention made it the standard at sea, along with SOS.
- Undersea cables. Long cables smear signals; a code that relies on fine timing distinctions (a four-unit dash versus a three-unit one) does not travel well.
- Everyone else was already using it. European telegraph administrations had standardised on Gerke’s code in the 1850s. American landlines were a large but isolated island.
American Morse nevertheless hung on in the United States and Canada for landline telegraphy into the 20th century — railway dispatchers were still using it in places into the 1960s — because a generation of operators had learned it and the sounders were built for it. A railroad telegrapher and a ship’s wireless operator in 1920 genuinely could not read each other’s code without retraining.
Speed and “swing”
One reason operators were fond of American Morse was speed: with its shorter digits and common letters, a skilled landline operator could send slightly faster than in International, and the internal spaces gave the code a characteristic rhythm or “swing” that experienced ears found pleasant. Modern enthusiasts who learn it describe the sound as recognisably different — jazzier, less metronomic — even at the same speed.
Which one should you learn?
International Morse, without hesitation. It is the only one used on amateur radio, in aviation beacons, in emergency signalling and by every modern app and translator. Learn it by ear using the method in How to Learn Morse Code, with the alphabet chart as a reference.
American Morse is worth knowing about — it explains the odd letters in old manuals, films set on 19th-century railways, and the design decisions behind the international code — and a small community of landline-telegraph enthusiasts still keeps it alive at museums and through the Morse Telegraph Club. But it is a historical curiosity, not a practical skill.
FAQ
Is American Morse code still used? Not for any practical purpose. It survives among historical telegraph enthusiasts and at railway museums, where you can sometimes hear it on original sounders.
Can an International Morse translator decode American Morse? No — many letters and most digits are different, and American Morse’s internal spaces cannot be represented with simple dots and dashes. Our translator handles International Morse only.
Why does American Morse have different numbers? The American digits were devised first and were somewhat ad hoc. Gerke regularised them into the neat five-signal pattern used in International Morse, which was then adopted worldwide.
Are SOS and CQ the same in both codes? SOS (··· −−− ···) is identical because S and O… almost: O differs in American Morse (it uses an internal space), so strictly the famous distress signal belongs to the international code — which is the one it was created for in 1906.