From telegraph wires to radio waves: the story of how dots and dashes changed global communications forever.
How a simple code revolutionized long-distance communication
Morse code is a method of encoding text characters as standardized sequences of two different signal durations, called dots and dashes (or dits and dahs). It was named after Samuel Morse, who co-developed the electrical telegraph system in the 1830s and 1840s.
International Morse code encodes the 26 basic Latin letters, the Arabic numerals, and a small set of punctuation and procedural signals. There is no distinction between upper and lower case letters in Morse code.
Each character in Morse code is represented by a unique sequence of dots and dashes. The dot duration serves as the basic unit of time measurement. A dash is three times as long as a dot. The space between elements of the same letter is equal to one dot, the space between letters is three dots, and the space between words is seven dots.
Though it bears his name, Morse code was not solely created by Samuel Morse. The American artist Samuel Morse, physicist Joseph Henry, and mechanical engineer Alfred Vail collaborated to develop an electrical telegraph system in the 1830s.
Around 1837, Morse developed an early version of the code, which was designed to make indentations on a paper tape when electric currents were received. The original design only transmitted numerals, and a codebook was required to look up each word according to the number transmitted.
Alfred Vail greatly expanded the code in 1840 to include letters and special characters, allowing for more general use. Interestingly, Vail determined the frequency of use of letters in English by counting the movable type in a local newspaper's type cases. The most commonly used letters were assigned the shortest codes, making Morse code surprisingly efficient.
The original Morse telegraph system made clicking noises as the electromagnetic receiver's armature struck a metal stop. Telegraph operators soon discovered they could translate these clicks directly into dots and dashes without needing to look at the paper tape, increasing efficiency.
As operators became more proficient, they began to recognize Morse code as complete sounds rather than individual dots and dashes. This audio recognition approach became the standard training method, with operators learning to hear Morse as a language rather than individual symbols.
With the introduction of radiotelegraphy, dots and dashes were transmitted as short and long tone pulses. Operators began to vocalize dots as "dit" and dashes as "dah" to reflect the sounds they heard. This audible learning technique remains the most effective way to master Morse code today.
The Morse code most people know today is not the original version developed by Morse and Vail. What we now call International Morse Code was actually derived from a much-improved proposal by Friedrich Gerke in 1848, known as the "Hamburg alphabet."
Gerke's version simplified American Morse code, which had different length dashes and different inter-element spaces, creating a more standardized system with only dots and dashes of uniform duration. The International Morse code was officially adopted at the International Telegraphy Congress in Paris in 1865.
The original American Morse code (sometimes called "Railroad Morse") continued to be used in the United States and Canada for land-line telegraphy until the 1970s, but International Morse became the worldwide standard, especially for maritime and radio communications.
Historical applications that shaped modern communications
The telegraph system using Morse code revolutionized long-distance communication. By the late 19th century, a vast network of telegraph wires connected cities and countries, creating the world's first telecommunications network.
Telegraph operators could transmit messages across continents at unprecedented speeds. This radically transformed how news, business information, and personal messages traveled, shrinking the world in ways previously unimaginable. The speed of information exchange via telegraph was so revolutionary that it was often described as "the Victorian Internet."
In the 1890s, as radio technology developed, Morse code found a new application. Radiotelegraphy using Morse code became the primary means of communication for ships at sea before voice transmission was possible.
Morse code was vital during both World Wars, especially for naval communications. Long-range ship-to-ship communication was conducted via radio telegraphy using encrypted Morse code messages, as voice radio systems were limited in range and security.
Until 1999, Morse code was the international standard for maritime distress calls, with SOS (• • • — — — • • •) being the universal distress signal. When the French Navy ceased using Morse code on January 31, 1997, their final message was poignantly simple: "Calling all. This is our last call before our eternal silence."
From the 1930s through the late 20th century, pilots were required to know Morse code for identification of navigational beacons. These beacons transmitted continuous two or three-letter identifiers that pilots would use to confirm they were following the correct route.
Aviation radio navigation aids such as VORs (VHF Omnidirectional Range) and NDBs (Non-Directional Beacons) still use Morse code identification signals today, though many now also provide voice identification as well.
In the aviation service, Morse is typically sent at a very slow speed of about 5 words per minute, making it easier for pilots to identify while handling other flight duties.
Morse code in the digital age
Today, Morse code is most popular among amateur radio operators, who use it in the mode commonly called "continuous wave" or "CW." Many amateur radio enthusiasts value Morse code for its efficiency and reliability, especially in poor signal conditions.
Until 2003, the International Telecommunication Union mandated Morse code proficiency as part of amateur radio licensing worldwide. Though this requirement has been dropped in most countries, many operators still learn and use Morse code as a point of pride and for its practical advantages.
Because Morse code transmissions use much less bandwidth than voice communication and can be decoded in very high noise conditions, it remains excellent for long-distance (DX) communication and for low-power transmissions.
The universally recognized distress signal SOS (• • • — — — • • •) remains one of the most important applications of Morse code. This can be sent using many methods: keying a radio on and off, flashing a mirror, toggling a flashlight, or using other improvised means.
Modern warships, including those of the U.S. Navy, still use signal lamps to exchange messages in Morse code. This serves as a backup communication method when radio silence must be maintained for tactical reasons.
Morse code has found important applications as an assistive technology for people with disabilities. For individuals with severe mobility limitations who retain some minimal motor control, Morse code provides a means to communicate electronically.
Modern technology has expanded these applications. For example, Android's Gboard keyboard includes a Morse code input option that allows users to compose text using just two input signals.
One advantage of Morse code for assistive technology is that once learned, it doesn't require visual feedback. Users can communicate by memory without needing to look at a display, making it particularly valuable for certain disabilities.
Beyond its technical applications, Morse code has made a lasting impression on popular culture. The rhythm of SOS has been incorporated into music and literature, and Morse code has appeared in countless films and television shows as a plot device.
Learning Morse code continues to be valued as a mental exercise, with studies suggesting it may help with cognitive development. The Boy Scouts of America still awards a Morse interpreter's strip to scouts who demonstrate proficiency in the code.
Though no longer essential for global communications, Morse code remains a fascinating link to communication history that continues to find new applications in the digital age.