American Morse Code vs International Morse Code
American Morse code is the original telegraph code. Today, when people say “Morse code,” they almost always mean International Morse, which replaced American Morse for most uses.
What is American Morse code?
American Morse, also called Railroad Morse, is the original version of the code. It was developed in the mid-1840s by Samuel Morse and Alfred Vail for their electric telegraph. It is now nearly extinct, and you are most likely to see it in American railroad museums and Civil War reenactments.
Key differences
- Internal spaces: American Morse uses longer gaps inside some letters. International Morse does not use these long internal gaps.
- Extra symbols: American Morse uses two long dashes that International Morse does not use.
- Standard: International Morse is defined by ITU-R M.1677-1.
Why International Morse replaced American Morse
In 1848, Friedrich Clemens Gerke created a simpler standard in Germany. It removed the long internal gaps and the two long dashes. Most of the rest of the world later adopted this simpler code, which is now called International Morse.
Which one should you learn?
Learn International Morse. It is the standard used in amateur (ham) radio and most modern contexts. American Morse code is mainly useful for historical study.
How American Morse was used
American Morse is also called Railroad Morse, because it was widely used on American railroad telegraph lines. The original code was developed in the mid-1840s by Samuel Morse and Alfred Vail for their electric telegraph. Over the following decades, American Morse was used on land telegraph networks, where operators often sent messages by sound, reading the clicks of a sounder by ear.
The American version uses symbols that are not used in International Morse. Because the symbols differ, the two systems are not interchangeable: a reader must learn the differences to switch between them.
Why International Morse became the standard
Most of the world eventually adopted International Morse, which removes the long internal gaps and the two extra long dashes of the American code. The simpler system is easier to learn and send. The version that became International Morse was standardized through international telegraph agreements, and today it is the code used in amateur (ham) radio, aviation navigation beacons, and emergency signals.
Where you can still see American Morse
American Morse is now nearly extinct. You are most likely to see it in American railroad museums, at Civil War reenactments, and in historical books and displays about the telegraph. If you want to study it, start with a chart of the original symbols and compare each letter with its International Morse equivalent.
Many learners ask whether American Morse code is worth learning. For most people today, the answer is no: International Morse is the standard in amateur radio and emergency signaling. Learning American Morse code can still help you read historical messages, understand the telegraph era, and see how the modern code evolved from its earlier form.
How to compare the two codes yourself
- Pick a short word, such as SOS, and write it in International Morse using our SOS page.
- Find the same letters in an American Morse chart, and note where the symbols or gaps differ.
- Practice only the International version for everyday use. Study American Morse as a historical reference.
For International Morse letters, see the Morse code alphabet page. For the timing rules behind the standard, see how Morse code works.
For the official rules that define International Morse, read the International Telecommunication Union recommendation ITU-R M.1677-1.
Frequently Asked Questions
Is American Morse still used?
Almost never. It is mainly studied for history.
What is the main difference?
American Morse code has longer gaps inside some letters and two extra long dashes. International Morse does not.
Which Morse code do ham radio operators use?
International Morse.
Related: History of Morse code, Morse code alphabet, how Morse code works.