American Morse Code vs International

Where the two codes came from

1844: Morse and Vail's code

Samuel Morse and Alfred Vail developed the first practical code for their electric telegraph in the late 1830s and early 1840s. On May 24, 1844, the message "What hath God wrought" traveled from Washington to Baltimore in it. Vail is generally credited with assigning the shortest codes to the most common letters after studying the type cases of a printer. Because the telegraph of the day recorded marks on paper tape, pauses inside a letter and dashes of varying length were easy to read by eye, and the code made free use of both.

1848: Gerke's revision

When the telegraph spread to Europe, Friedrich Clemens Gerke, a telegraph inspector in Hamburg, rewrote the code in 1848 for the Hamburg–Cuxhaven line. He removed the internal spaces and the long dashes, kept a single dot and a single dash, and changed the codes of about half the letters and all the numbers. Gerke's version, known as "Continental Morse", was adopted by the German-Austrian Telegraph Union in 1851 and was standardized internationally at the International Telegraph Convention in Paris in 1865, the meeting that founded what is now the ITU.

Why International won

Operators soon learned to copy Morse by ear instead of reading tape, and by ear the American code's internal pauses are ambiguous: is . . an O, or an E followed by an E? Radio made the problem worse, because static can swallow the difference between a dash and a long dash. A code with only two elements and no silence inside a letter was more robust, so radio adopted International Morse from the start, and the 1912 radiotelegraph convention made it the worldwide standard at sea.

Where American Morse survived

The United States and Canada kept the original code on their landline telegraph networks, which is why it is also called "Railroad Morse". Railroad dispatchers, Western Union offices and press wires used it long after the rest of the world had switched, and skilled American operators were famous for the speed they achieved with it. It finally died out with the landline telegraph itself in the 1960s, as teleprinters and telephones replaced the key. Today it is kept alive by railroad museums, telegraph re-enactors and hobbyist groups such as the Morse Telegraph Club, who still hold "wire" sessions in the old code.

Everything else, from amateur radio and aviation beacons to Gboard's Morse keyboard and the translator on this site, uses International Morse. If you are learning Morse code today, that is the one to learn; the alphabet page and printable chart cover it completely.