When most people say "Morse code" today, they mean International Morse, the code defined in ITU-R M.1677-1 and used from ham radio to aviation beacons. It is not the original. The code that opened the first American telegraph line, now called American Morse or "Railroad Morse", came first and looks surprisingly different.
Here's what is different between the two, what the sources say about how the change happened, and where the old code survives.
American Morse: the original
Samuel Morse first planned a code of numbers only, looked up in a codebook. Alfred Vail expanded it to letters in 1840, and the official first message, "What hath God wrought", went from the U.S. Capitol in Washington to Baltimore on May 24, 1844.
American Morse has more kinds of building block than the code we use now:
- Dots and dashes, as in International Morse.
- A long dash for the letter L, and an even longer one for the numeral 0.
- Gaps inside letters. C, O, R, Y, Z and & contain a longer pause in the middle. O is dot, pause, dot, which is easy to mistake for two Es; C is two dots, a pause, then one more dot.
International Morse: the simplified rebuild
In 1848 Friedrich Clemens Gerke reworked the code for the telegraph line between Hamburg and Cuxhaven in Germany. He changed nearly half the alphabet and all of the numerals, and did away with the different dash lengths and the gaps inside letters. A version of Gerke's code was standardised by the International Telegraph Convention in Paris in 1865, and it became International Morse.
The result:
- One length of dash instead of three.
- No gaps inside a letter: every letter is one continuous pattern.
- New patterns for many letters and every digit.
This is the code on our chart, on /morse-code/, and in every modern reference.
The letters that differ
Eleven of the 26 letters are different. In the American column, a wider gap marks the pause inside the letter.
| Letter | American | International |
|---|---|---|
| C | ·· · | -·-· |
| F | ·-· | ··-· |
| J | -·-· | ·--- |
| L | a long dash | ·-·· |
| O | · · | --- |
| P | ····· | ·--· |
| Q | ··-· | --·- |
| R | · ·· | ·-· |
| X | ·-·· | -··- |
| Y | ·· ·· | -·-- |
| Z | ··· · | --·· |
The other 15 letters, including E (one dot) and T (one dash), are the same in both codes. Notice how often the American patterns reuse a pattern that means something else in International Morse: American F is International R, and American Q is International F. Anyone who knows one code will misread the other.
Why the US kept American Morse
International Morse became the rule for radio: the 1912 London Radiotelegraph Convention specified it for radio signals. But on land, American Morse remained the standard for U.S. telegraph companies, including the dominant one, Western Union. One reason given is speed: American Morse could be sent about 5% faster than International. American Morse was also still common for domestic radio on the Great Lakes and the U.S. coasts, while International Morse dominated on ocean-going ships.
American Morse faded as landline telegraphy disappeared. Today it is heard mostly at railroad museums, at historical demonstrations, and among a small group of telegraph enthusiasts.
Where the old system still echoes
- 73 and 30. Western Union adopted its "92 Code" of numbered shorthand messages in 1859. Its list gives 73 as "I wish you well" or "best regards", and 30 as "no more, the end". Radio amateurs still sign off with 73, and journalists used "-30-" to mark the end of a story. See the 73 page.
- Railroad and Civil War history. Re-enactors and museums that demonstrate period telegraphy use American Morse, because that is what the operators of the time sent.
The one-line takeaway
American Morse was the first working code and stayed in use on American telegraph lines for a long time; International Morse is the simplified version that the rest of the world, and all radio, settled on.
For learning: start with International Morse and the Koch trainer. Learn American Morse only if you want to work with historical telegraph equipment, and don't mix the two, because the same patterns mean different letters.