|This article does not cite any references or sources. (June 2007)|
An interesting description of these early 19th century methods and its evolution into the electrical telegraph networks of the mid-to-late 19th century is found in The Victorian Internet, a book by Tom Standage ISBN 0-425-17169-8.
Radio relay leagues
Radio amateur message relay operations were originally conducted using Morse code in the first two decades of the 20th century using spark-gap transmitters. As vacuum tubes became affordable operations shifted to more efficient manual telegraphy transmitters, referred to as CW (Continuous wave). Messages were relayed station to station typically covering four or more re-transmission cycles to cover the continental United States, in an organized system of amateur radio networks. After World War II, voice and radioteletype implementations of the message relay system were employed.